Paper 3 Higher

PrepWiseGuide to a real paper

OCR B GCSE Physics

Paper 3 Higher

June 2025
90 marks · 1 hour 45 minutes · 9 questions

A real paper, in its real order. Each description and answer is ours, so you can see how each mark is earned. Not made or approved by OCR B.

The real exam gives you an equations sheet. See the equations

PrepWise guide: OCR B GCSE Physics Paper 3 HigherQuestion 1

A boat travels along a canal from A to C and passes B on the way. Figure 1 is a scale plan of the canal as a straight line, with a strip of equal divisions beneath for measuring. In total the boat covers 5000 m between A and C. Figure 2 gives four rows of graphs for the boat's departure, and Figure 3 plots its speed over a short spell.

Figure 1
A straight horizontal line representing a canal, with three dots on it labelled A, B and C from left to right. A strip of equal, unnumbered divisions runs beneath the line so the distances between the dots can be measured.
Figure 2
A table of four rows labelled Row A to Row D. Each row holds a small distance-time graph on the left and a small speed-time graph on the right, each with labelled axes and no numbers, and each drawn as a single line or curve.
Figure 3
A graph of speed in metres per second up the vertical axis and time in seconds along the horizontal axis, on a numbered grid. One straight line is drawn across the grid.
01.1[2 marks]

Use Figure 1 and its strip to find how far the boat goes from A to B.

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Measure with the strip:. AB = 4 divisions. AC = 10 divisions

Scale the 5000 m by the ratio:. AB = 4 over 10 × 5000. AB = 2000 m

2 marks

How the marks are earned

  1. One mark: measure both stretches on Figure 1, A to B and A to C, or write them as a ratio. Readings within 0.2 of a division on either stretch are fine.
  2. One mark: scale the 5000 m by that ratio to get the A to B distance, which is 2000 m. Any answer from 1670 m to 2370 m is accepted.
  3. The correct answer, 2000 m, on the answer line earns both marks with no working.

Why it scores

The plan is drawn to scale, so the lengths on it share the same ratio as the real distances. Comparing two lengths needs no unit, so the size of the divisions does not matter.

B is four tenths of the way along the route, so the real distance is four tenths of 5000 m. Writing 2000 m alone, with no working, still earns both marks.

Revise Newton's Laws of Motion
01.2[3 marks]

The boat leaves A at 09:23 and reaches B at 09:53. Using your A to B distance, find its average speed in m/s.

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Change the time to seconds:. time = 30 × 60. time = 1800 s

Use the rule for average speed:. speed = distance over time. speed = 2000 over 1800

Evaluate:. speed = 1.1 m/s

3 marks

How the marks are earned

  1. One mark: change the journey time into seconds. From 09:23 to 09:53 is 30 minutes, so the time is 1800 s.
  2. One mark: divide your distance from the previous part by that time, for example 2000 ÷ 1800. Using 30 instead of 1800 earns this one mark at most, and no final mark.
  3. One mark: the speed, 1.1 m/s (1.11 unrounded). An answer of 1 m/s counts only when the working or the unrounded value is shown.
  4. The correct answer, 1.1 m/s, on the answer line earns all three marks.

Why it scores

Speed in m/s needs the time in seconds. Leaving it as 30 would give a number that is 60 times too big, and the final mark would be lost.

Average speed is the total distance divided by the total time. Your own distance from the previous part is used, so a slightly different measurement still earns this mark.

2000 ÷ 1800 = 1.11, which is 1.1 m/s to 2 significant figures. The right answer alone earns all 3 marks.

Revise Newton's Laws of Motion
01.3[1 mark]

Use Figure 2 to pick the row for a boat that speeds up at a steady rate, then keeps constant speed.

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Row A
Row B
Row C
Row D
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Row C is the one. Steady acceleration is a straight rising line on a speed-time graph, and constant speed is a flat line. On the distance-time graph the gradient is the speed, so it steepens while the boat speeds up, then stays constant as a straight sloping line.

1 mark

How the marks are earned

  1. Tick Row C: its speed-time graph climbs in a straight line and then goes flat, and its distance-time graph curves upwards and then becomes a straight sloping line.
  2. One box only: two ticks earn nothing.

Why it scores

Row A has a curved speed-time start, which means the acceleration itself is changing. Row B and Row D have distance-time graphs that go flat, which means the boat has stopped, not that it keeps moving at constant speed.

Revise Newton's Laws of Motion
01.4[3 marks]

Figure 3 plots the boat's speed against time. Work out the boat's acceleration in m/s2.

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The slope of a speed-time line is the acceleration:. a = rise over run

Read the line at the start and end: 0.8 m/s at 0 s and 1.2 m/s at 8 s.. acceleration = fraction: 1.2 − 0.8 over 8, end of fraction. acceleration = 0.4 over 8

Evaluate:. acceleration = 0.05 m/s2

3 marks

How the marks are earned

  1. One mark: use the gradient method, such as a triangle drawn on the line, or the rule acceleration = change in speed ÷ time. Dividing the speed by the time earns nothing.
  2. One mark: read two points correctly from the line, to within half a small square, and use their differences, for example (1.2 − 0.8) ÷ 8.
  3. One mark: the acceleration, 0.050 m/s2. Any answer from 0.045 to 0.055 is accepted.
  4. The correct answer, 0.05 m/s2, on the answer line earns full marks.

Why it scores

This earns the method mark. Drawing a right-angled triangle under the line, or writing the equation, both show the method. Dividing a single speed by a time would not.

Use points far apart so the reading error is small. Any other pair on the line, such as 0.9 m/s at 2 s and 1.1 m/s at 6 s, gives the same answer.

This earns the final mark. The right answer alone, with no working, earns all 3 marks.

Revise Newton's Laws of Motion
01.5[1 mark]

A breeze acts on the boat. Choose the everyday wind speed from the four values given.

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Roughly 0.12 metres per second
Roughly 12 metres per second
Roughly 1200 metres per second
Roughly 120 000 metres per second
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A typical wind blows at about 12 m/s, which is roughly 40 km/h. Winds of 1200 m/s and 120 000 m/s are far beyond anything the atmosphere produces. A breeze of 0.12 m/s would be almost still air.

1 mark

How the marks are earned

  1. Tick 12 m/s, a typical speed for a strong breeze.
  2. One box only: two ticks earn nothing.
Revise Newton's Laws of Motion
OCR B owns the copyright in its exam questions, so we cannot copy their wording. These descriptions and answers are ours. Not made or approved by OCR B.[10 marks]
PrepWise guide: OCR B GCSE Physics Paper 3 HigherQuestion 2

In the 1930s scientists bombarded uranium with neutrons. There were four steps on the way. Enrico Fermi's 1934 experiment sent neutrons into uranium; its nuclei absorbed them and changed into other elements, which he took to be heavier than uranium. Also in 1934 Ida Noddack proposed that the products could weigh less than uranium, yet her paper was ignored because it offered neither an experiment nor a theory. Otto Hahn redid Fermi's work in 1939 and found barium, a lighter element, among the products. The same year Lise Meitner worked through the energy changes in Hahn's data and found that the totals balance as a uranium nucleus breaks into barium and one other nucleus, so energy is conserved.

02.1[2 marks]

Choose the word for each gap: nuclei that split are ___, and the process is called nuclear ___.

See how you would score on Nuclear Fission & Fusion
fission
fusion
negative
power
stable
unstable
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Unstable fills the first gap.

Fission fills the second gap.

2 marks

How the marks are earned

  1. One mark: the first gap is unstable.
  2. One mark: the second gap is fission.

Why it scores

A large nucleus such as uranium is not held together firmly, so it can break into two smaller nuclei. A stable nucleus would not split.

Fission means splitting a large nucleus into smaller ones. Fusion is the opposite process, joining small nuclei into a larger one.

Revise Nuclear Fission & Fusion
02.2[1 mark]

Suggest why most scientists believed Fermi's idea in 1934, using the timeline in the context.

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Fermi had experimental results to back his idea, while Noddack had none. A nucleus that takes in a neutron gains mass, so it was reasonable to think the new elements were heavier than uranium.

1 mark

How the marks are earned

  1. Any one reason: absorbing a neutron makes a nucleus heavier; Fermi had experimental results; Fermi was already well known; Noddack had no data; or attitudes to women in science at that time.
  2. Saying that Fermi had shown nuclei could be split earns nothing.
Revise Nuclear Fission & Fusion
02.3[2 marks]

Use the timeline to explain why more scientists trusted the nuclear splitting idea by 1940.

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By 1939 Hahn had run Fermi's experiment again and got a result that others could check. Fresh experiments gave more evidence than the single 1934 result.

Hahn found barium among the products, a lighter element than uranium, and Meitner's calculation showed that the energy balances when uranium splits into barium and another nucleus.

2 marks

How the marks are earned

  1. One mark: there was fresh evidence, since Hahn's repeat of Fermi's experiment showed the result could be reproduced, or further experiments tested the idea.
  2. One mark: one piece of support from the timeline: barium, a lighter element than uranium, was found; or Meitner's calculation showed that energy is conserved in the split.
  3. Saying that science keeps developing, or only that energy is conserved, earns nothing.

Why it scores

An idea becomes trusted when other scientists can repeat the experiment and find the same thing. This earns the first mark.

Barium could only appear if uranium nuclei had split, and the energy calculation showed that the splitting obeyed a law that must hold. Either piece of evidence earns the second mark.

Revise Nuclear Fission & Fusion
02.4[1 mark]

Pick the account of how uranium splitting sets off a self-sustaining chain of splits.

See how you would score on Nuclear Fission & Fusion
The released neutrons are taken in by further uranium nuclei
The released neutrons spread harmful material around the surroundings
The released neutrons join end to end into a chain
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The first box. Each splitting nucleus gives out neutrons, and each of those can be absorbed by another uranium nucleus and make it split too, so the reaction keeps itself going. Neutrons do not link together, and spreading harmful material is a separate hazard, not the mechanism of the chain.

1 mark

How the marks are earned

  1. Tick the box about further uranium nuclei taking in the neutrons given out, and then splitting in their turn.
  2. One box only: two ticks earn nothing.
Revise Nuclear Fission & Fusion
02.5[2 marks]

Choose two statements on how a splitting uranium nucleus gives out its energy.

See how you would score on Nuclear Fission & Fusion
The new particles carry the energy away as motion
The original uranium nuclei carry the energy as motion
Energy is held as potential energy in the new particles
Infrared radiation is emitted
Ionising radiation is emitted
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The new particles fly apart at high speed, so the energy appears as their kinetic energy. The splitting also gives out ionising radiation, such as gamma rays.

2 marks

How the marks are earned

  1. Tick exactly two boxes. One mark for the box about the movement energy of the new particles.
  2. One mark for the box about giving out ionising radiation.

Why it scores

Each correct box earns one mark. The original nuclei no longer exist after the split, so they cannot carry the energy. Stored energy and infrared are not how the energy leaves the split.

Revise Nuclear Fission & Fusion
OCR B owns the copyright in its exam questions, so we cannot copy their wording. These descriptions and answers are ours. Not made or approved by OCR B.[8 marks]
PrepWise guide: OCR B GCSE Physics Paper 3 HigherQuestion 3

A spring is pulled by a force, and its extension depends on that force in a linear way.

03.1[2 marks]

Complete the idea: in a linear system, say what happens to the extension for each extra 1 N of force.

See how you would score on Forces & Their Effects
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Each extra 1 N makes the extension increase by the same amount, so the extension rises in equal steps.

2 marks

How the marks are earned

  1. One mark: the extension (or length) of the spring goes up.
  2. One mark: it goes up in equal steps, or in proportion. Stating the same increase in extension for each newton earns both marks, and an increase of 1 unit, for example 1 cm, is accepted for this second mark. Saying the extension is squared earns nothing, and mentioning the spring constant is ignored.

Why it scores

The first mark is for saying the extension increases. The second is for the equal steps, which is what makes the relationship linear, a straight line on a force-extension graph. The extension must not be squared or changed in some other way.

Revise Forces & Their Effects
03.2[4 marks]

A spring has spring constant 15 N/m and extension 0.01 m. Find the energy stored, in standard form, in J.

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Choose the equation:. energy = ½ × spring constant × extension2

Substitute:. energy = ½ × 15 × 0.012. energy = ½ × 15 × 0.0001

Evaluate:. energy = 0.00075 J

Standard form has one digit before the point:. 0.00075 = 7.5 × 10-4 J

4 marks

How the marks are earned

  1. One mark: choose the equation energy stored = ½ × spring constant × extension2. A correct substitution also earns this mark.
  2. One mark: substitute: ½ × 15 × 0.012.
  3. One mark: the value 0.00075 J.
  4. One mark: write that value in standard form, 7.5 × 10-4 J. Clear working that gives a wrong number, correctly written in standard form, earns this mark, for example 7.5 × 10-2 from forgetting to square.
  5. A correct answer in standard form with no working is worth at least three of the four marks, so show your working.

Why it scores

This earns the equation mark. The work is choosing it and noticing that the extension is squared.

Square the extension first: 0.01 × 0.01 = 0.0001. Leaving out the squaring is the common slip and gives an answer 100 times too big.

7.5 × 0.0001 = 0.00075, which earns the value mark.

Standard form has one non-zero digit before the decimal point, here 7.5, times a power of ten. The decimal point moves four places, so the power is −4.

Revise Forces & Their Effects
OCR B owns the copyright in its exam questions, so we cannot copy their wording. These descriptions and answers are ours. Not made or approved by OCR B.[6 marks]
PrepWise guide: OCR B GCSE Physics Paper 3 HigherQuestion 4

Sound and light are both wave motions. In Figure 4 a white light ray heads for a flat mirror. In Figure 5 white light goes through a glass prism and lands on a screen.

Figure 4
A plane mirror drawn as a horizontal line with hatching underneath it, and one straight ray with an arrowhead arriving at the mirror from the upper left. No other lines, normal or angle labels are drawn.
Figure 5
A triangular glass prism with one narrow ray of white light meeting its left face. At that point the ray splits into a fan of seven separate rays inside the glass, spreading out slightly as they cross it. Each ray leaves the right face at its own point, close together, and the fan opens out as it runs on to a vertical screen on the right, ending at seven separate points on it. The seven ray names are listed beside the screen.
04.1[3 marks]

Describe what to add to Figure 4: the normal, the reflected ray, and labels for the two angles.

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Add the normal: a dashed line perpendicular to the mirror, starting at the spot the incoming ray strikes, and write N beside it.

Draw the reflected ray from that point, leaning away on the other side of the normal, with the same angle to the normal as the incident ray.

Mark i between the incident ray and N, and r between the reflected ray and N.

3 marks

How the marks are earned

  1. One mark: a perpendicular to the mirror surface, standing on the point of impact of the ray. A perpendicular placed at any other point of the mirror earns nothing.
  2. One mark: the reflected ray leaves that same spot on the other side of the normal, at an angle that looks equal to the incoming ray's angle, by eye. Arrowheads on the rays are ignored.
  3. One mark: both angles carry a label, for example i and r or θi and θr, and each is marked against the normal. An angle drawn against the mirror surface itself earns nothing.

Why it scores

All angles in reflection are measured from the normal, so it comes first. It must start at the point of incidence, not elsewhere on the mirror.

The law of reflection says angle of incidence equals angle of reflection. A careful drawing by eye is accepted, so no protractor is needed.

These labels earn the last mark. An angle drawn between a ray and the mirror itself does not count, because angles are measured from the normal.

Revise Reflection & Refraction
04.2[2 marks]

Tick the two words that describe light waves.

See how you would score on Wave Properties
Compression
Electromagnetic
Longitudinal
Radioactive
Seismic
Transverse
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Light is an electromagnetic wave, and it is a transverse wave, with oscillations at right angles to the direction it travels.

2 marks

How the marks are earned

  1. Tick exactly two boxes. One mark for Electromagnetic.
  2. One mark for Transverse.

Why it scores

Each correct box earns one mark. Compression and longitudinal describe waves such as sound. Radioactive describes unstable nuclei, and seismic describes waves from earthquakes.

Revise Wave Properties
04.3[2 marks]

Figure 5 shows white light through a glass prism. Explain why the light spreads into colours.

See how you would score on Reflection & Refraction
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White light is a mixture of colours, and each colour has its own frequency and wavelength.

In glass each colour travels at a different speed, so each bends by a different amount when it enters and leaves the prism, and the colours fan out.

2 marks

How the marks are earned

  1. One mark: the colours in white light have different wavelengths or frequencies.
  2. One mark: each colour travels at a different speed inside the glass, so each is refracted by a different amount. Saying each colour refracts by a different amount alone is accepted for this mark.
  3. Saying that red has the longer wavelength so is refracted least earns both marks. Saying the colours differ in amplitude earns nothing, and neither does saying red has the shortest wavelength or violet the lowest frequency.

Why it scores

This earns the first mark. It is the frequency and wavelength, never the amplitude, that tells the colours apart.

This earns the second mark. Red has the longest wavelength of the visible colours and refracts least, while violet has the shortest and refracts most.

Revise Reflection & Refraction
04.4[3 marks]

Orange light has frequency 5.0 × 1014 Hz and wavelength 400 × 10-9 m in glass. Find its speed in m/s.

See how you would score on Wave Properties
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Choose the equation:. wave speed = frequency × wavelength

Substitute:. wave speed = 5.0 × 1014 × 400 × 10-9

Evaluate:. wave speed = 200 000 000 m/s. wave speed = 2 × 108 m/s

3 marks

How the marks are earned

  1. One mark: choose wave speed = frequency × wavelength. A correct substitution also earns this mark.
  2. One mark: substitute: 5.0 × 1014 × 400 × 10-9.
  3. One mark: the answer, 2 × 108 m/s (200 000 000).
  4. The correct answer, 2 × 108 m/s, on the answer line earns full marks.

Why it scores

This earns the equation mark. It is the rule that links wave speed, frequency and wavelength.

The numbers go in as they are given, with the wavelength already in metres. Writing this line without the equation above it still earns the first two marks.

5.0 × 400 = 2000 and 1014 × 10-9 = 105, so the product is 2000 × 105 = 2 × 108. The right answer alone earns all 3 marks.

Revise Wave Properties
04.5[3 marks]

Match each medium (air, vacuum, water, steel) to the speed of sound in it, using the four speeds listed.

See how you would score on Sound Waves
0 metres per second
Roughly 330 metres per second
Roughly 1500 metres per second
Roughly 5000 metres per second
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Air goes with 330 m/s, vacuum with 0 m/s, water with 1500 m/s and steel with 5000 m/s.

3 marks

How the marks are earned

  1. Match each medium to its own speed: air 330 m/s, vacuum 0 m/s, water 1500 m/s, steel 5000 m/s.
  2. All four matches correct earn 3 marks, three correct earn 2 marks, and two correct earn 1 mark.

Why it scores

Sound is a vibration of particles, so it travels faster where the particles are packed more closely. Of the three media that carry sound, it is slowest in air, faster in liquid water and fastest in solid steel. A vacuum has no particles, so sound cannot travel through it at all, giving a speed of 0 m/s.

Revise Sound Waves
OCR B owns the copyright in its exam questions, so we cannot copy their wording. These descriptions and answers are ours. Not made or approved by OCR B.[13 marks]
PrepWise guide: OCR B GCSE Physics Paper 3 HigherQuestion 5

Marie Curie found radioactive elements by taking them out of their ores. Radium has contaminated her notebook, which still gives out radiation. Figure 6 charts a radium sample's activity in counts per second (cps). The curve starts roughly 4000 years before the year 2000, and a dashed line marks the present day.

Figure 6
A graph of activity in counts per second up the vertical axis and time from the year 2000 in years along the horizontal axis, on a fine numbered grid. One smooth curve crosses the grid, and a dashed vertical line marks the present day.
05.1[3 marks]

Give radium's half-life in years, working from the curve in Figure 6.

See how you would score on Half-Life
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Half-life is the time for the activity to fall to half. Take the activity at the left of the graph, 3400 cps, and half of it, 1700 cps.

Read across to the curve and down to the time axis:. 3400 cps is at −4000 years. 1700 cps is at −2400 years

Find the gap between the two readings:. half-life = −2400 − (−4000). half-life = 1600 years

3 marks

How the marks are earned

  1. One mark: read two activities from the curve where one is half of the other, such as 3400 cps and 1700 cps.
  2. One mark: read the two times that go with them, such as 4000 years and 2400 years before the year 2000.
  3. One mark: the gap between those times, 1600 years. A correct time gap for any other activity change, such as 4000 years from 3400 cps down to 600 cps, earns one mark. A bare 2400 earns nothing.
  4. The correct answer, 1600 years, on the answer line earns full marks.

Why it scores

Choose a start where the curve is easy to read. Any start works, because the activity halves in the same time wherever you begin.

The times are measured from the year 2000, so the earlier time is more negative. Read both values to the nearest small square.

The gap between the two times is the half-life. The right answer alone earns all 3 marks.

Revise Half-Life
05.2[2 marks]

The notebook's radium has about 600 cps today. Find its activity after three more half-lives, in cps.

See how you would score on Half-Life
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Three halvings, one after another:. 600 × ½ = 300. 300 × ½ = 150. 150 × ½ = 75

Check with the fraction left, one eighth:. activity = 600 over 8. activity = 75 cps

2 marks

How the marks are earned

  1. One mark: working that halves three times, such as 600 to 300 to 150, or the fractions one half, one quarter, one eighth. Halving three times earns this whatever the starting number.
  2. One mark: the activity, 75 cps.
  3. The correct answer, 75 cps, on the answer line earns both marks.

Why it scores

Each half-life halves the activity. Writing the three halvings earns the first mark.

Three halvings leave ½ × ½ × ½ = ⅛ of the activity. The right answer alone earns both marks.

Revise Half-Life
05.3[1 mark]

Find the fraction of the radium nuclei that decay during those three half-lives.

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After three half-lives, one eighth of the nuclei are left:. fraction decayed = 1 − 1 over 8. fraction decayed = 7 over 8. In decimals that is 0.875.

1 mark

How the marks are earned

  1. The fraction is 7/8 (or 0.875). A working such as 525 ÷ 600 is also accepted.
Revise Half-Life
05.4[2 marks]

Say how the danger from handling the notebook a century ago compares with the danger now.

See how you would score on Half-Life
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The notebook was about as hazardous 100 years ago as it is now, and only very slightly more hazardous then.

100 years is a small part of one half-life:. 100 over 1600 = 0.0625. So very little of the radium has decayed and its activity has hardly fallen.

2 marks

How the marks are earned

  1. One mark: it was about as hazardous then as now, or slightly more hazardous 100 years ago, which is the same as slightly less hazardous today; saying slightly less hazardous today alone is also accepted. Saying only more or less, with no qualifying word, earns nothing.
  2. One mark: the reason is that 100 years is short compared with the half-life of 1600 years, about 0.06 of a half-life, so the activity has barely changed. Saying both activities are about 600 cps, the activity is the same, or the activity has not dropped much is also accepted, and so is a quoted drop of between 5 and 50 cps.

Why it scores

This earns the first mark. Saying simply that it was more hazardous or less hazardous, with no qualifier, does not.

The hazard depends on the activity, which falls by half only after 1600 years. Saying the activity is about the same, around 600 cps, also earns this mark.

Revise Half-Life
OCR B owns the copyright in its exam questions, so we cannot copy their wording. These descriptions and answers are ours. Not made or approved by OCR B.[8 marks]
PrepWise guide: OCR B GCSE Physics Paper 3 HigherQuestion 6

A loudspeaker contains a permanent magnet and a wire coil, drawn side-on in Figure 7. Figure 8 is a cross-section through the magnet, cut across its length, and Figure 9 adds a single turn of the coil near its centre.

Figure 7
Side view of a loudspeaker. A permanent magnet with a south pole at the top, a north pole in the middle and a south pole at the bottom sits on the left. A coil of wire wound around the middle section is attached to a wide cone that flares out to the right. A dashed vertical line X to X cuts through the magnet. Labels name the permanent magnet, coil of wire and cone.
Figure 8
A circular cross-section. A small disc in the centre is labelled N. Around it is a wide ring, labelled S at eight places, with a gap of empty space between the disc and the ring. No field lines are drawn.
Figure 9
A round cross-section like Figure 8, with a centre disc marked N and an outer ring marked S at eight spots. In the space between them sits one thin circle for a single coil turn, carrying four small arrowheads, with a leader line to a text label for the coil's current.
06.1[2 marks]

On Figure 8, state what four field lines from the magnet must look like, and which way their arrows point.

See how you would score on Magnetic Fields
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Draw four short straight lines like the spokes of a wheel, each running from the central north pole across the gap to the south pole ring.

Put an arrowhead on every line pointing outwards, from the north pole towards the south pole.

2 marks

How the marks are earned

  1. One mark: four lines drawn straight outwards from the north pole in the middle to the south pole ring, along radii of the circle. Any curve in a line loses the mark.
  2. One mark: an arrowhead on each line pointing outwards, from the north pole to the south pole. An arrow pointing away from the south pole earns nothing.

Why it scores

The field in the gap points straight across from one pole to the other. Because the poles are circular and facing, the lines are straight and run along the radii, with no curving.

Magnetic field lines always point from north to south. An arrow pointing in, towards the centre, would show the opposite direction.

Revise Magnetic Fields
06.2[3 marks]

An alternating current runs in the coil in Figure 9; explain what makes the coil experience a push.

See how you would score on The Motor Effect
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A current in a wire produces a magnetic field around the wire.

The coil lies in the strong field of the permanent magnet, which acts across the gap.

Because the current crosses the magnet's field at 90 degrees, the two fields interact and push on the wire. That is the motor effect, which Fleming's left-hand rule predicts.

3 marks

How the marks are earned

  1. One mark: the current in the wire creates its own magnetic field. The wire becoming magnetised is accepted. Just saying there is a current, that the wire is magnetic, that it becomes a magnet, or that a magnetic force is induced earns nothing.
  2. One mark: the coil sits inside the magnetic field of the fixed magnet. A statement that the permanent magnet has a field is also accepted.
  3. One mark: the two fields interact, or the current is at right angles to the field, or the left-hand rule or the motor effect is named. Attraction or repulsion with the permanent magnet is accepted. Any reference to an electric field, or to the interaction creating a current or a p.d. in the wire, earns nothing.

Why it scores

This earns the first mark. It is the moving charges in the wire that make a field of their own.

This earns the second mark. A force needs a wire carrying current inside another magnetic field.

This earns the third mark. Attraction and repulsion between the coil's field and the magnet's field also count. The interaction produces a force, not a current.

Revise The Motor Effect
06.3[3 marks]

Explain how the coil's push produces sound that matches the supply's alternating current in frequency.

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The alternating current keeps reversing, so the force on the coil keeps reversing too, and the coil moves back and forth.

The coil is attached to the cone, so the cone vibrates and pushes the air, making compressions and rarefactions. These travel as a longitudinal sound wave with the frequency of the current.

3 marks

How the marks are earned

  1. One mark: the coil vibrates, moving back and forth.
  2. Any two further marks from: the field around the coil keeps varying; the push on the coil flips direction each time the current reverses (being attracted and repelled by the magnet is accepted here); the cone attached to the coil vibrates too; the cone drives the air into compressions and rarefactions; the air carries a longitudinal wave; the air particles oscillate at the frequency of the current.
  3. Vibrations travelling through the air are accepted for the wave. Any reference to induction caps the answer at 2 marks.

Why it scores

This earns the vibration mark. Each reversal of the current gives one reversal of the force, so the coil vibrates at the same frequency as the current.

With the vibration mark, any two of the further points complete the 3 marks. The air vibrates at the cone's frequency, which is why the pitch of the sound matches the alternating current.

Revise Sound Waves
06.4[4 marks]

Find the force on one coil of the speaker: field strength 1.2 T, current 0.3 A, coil circumference 5 cm.

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Change the length to metres:. length = 5 over 100. length = 0.05 m

Choose the equation:. force = magnetic field strength × current × length

Put the numbers in:. F = 1.2 T × 0.3 A × 0.05 m

Evaluate:. force = 0.018 N

4 marks

How the marks are earned

  1. One mark: change 5 cm into 0.05 m.
  2. One mark: choose force = magnetic field strength × current × length, F = BIL. A correct substitution also earns this mark.
  3. One mark: put the numbers in, 1.2 for the field strength, 0.3 for the current and your own converted length for the wire. A correct substitution that uses a wrong conversion still earns this mark and the select-equation mark.
  4. One mark: the force, 0.018 N.
  5. The correct answer, 0.018 N, on the answer line earns full marks.

Why it scores

The equation needs the length in metres to give a force in newtons. Leaving it as 5 would make the answer 100 times too big.

This is the equation mark. The length is the wire inside the field, which for one turn is the coil's circumference.

This earns the substitution mark, whichever way round the factors are written.

1.2 × 0.3 = 0.36 and 0.36 × 0.05 = 0.018. The right answer alone earns all 4 marks.

Revise The Motor Effect
06.5[3 marks]

Suggest three ways to make the force on the speaker's coil bigger.

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Wind extra turns on the coil, raise the current, and fit a stronger magnet.

3 marks

How the marks are earned

  1. Any three from: more turns of wire on the coil; a larger current; a stronger magnet (a stronger magnetic field); an iron core, a magnetic core, or soft magnetic material.
  2. One mark each. A steel core earns nothing, and neither does an unqualified core. Voltage counts only if linked to a larger current. A larger or wider coil counts only if linked to more wire in the field.

Why it scores

The force depends on field strength, current and wire length, so each change raises one of them. Extra turns put more wire inside the field. Any three correct ways earn the marks, so a soft iron core in the coil, which is magnetised easily and strengthens the field, would also count.

Revise The Motor Effect
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PrepWise guide: OCR B GCSE Physics Paper 3 HigherQuestion 7

Pedalling an exercise bike spins a magnet within a coil, so a potential difference is induced in a circuit. Figure 10 plots that potential difference against time during a ride.

Figure 10
A graph of potential difference in volts on the vertical axis, which extends both above and below the horizontal time axis, with time in seconds along the horizontal axis. One repeating smooth curve is drawn, two cycles long, and each cycle touches the time axis at its ends.
07.1[1 mark]

Choose what the coil must connect to so the circuit carries direct current.

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An ammeter
A pair of slip rings
A commutator made from a split ring
A simple on/off switch
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A split ring commutator. It swaps the connections to the coil every half turn, so the current in the circuit always goes the same way round. Slip rings keep the connections steady, so the output stays alternating. An ammeter only measures current, and a switch only turns it on or off.

1 mark

How the marks are earned

  1. Tick the commutator made from a split ring.
  2. One box only: two ticks earn nothing.
Revise Electromagnetic Induction
07.2[1 mark]

Use Figure 10 to choose the feature showing that direct current is produced.

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The potential difference peaks at the same value every time
The potential difference is never negative
The potential difference falls to zero in every cycle
The potential difference changes as time goes on
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A potential difference that never goes below the time axis always pushes current the same way round, which is direct current. Alternating current would swing below the axis, giving negative values. A repeating peak, a drop to zero, and a change over time all happen with alternating current too, so they cannot show direct current.

1 mark

How the marks are earned

  1. Tick the option saying the potential difference never goes negative.
  2. One box only: two ticks earn nothing.
Revise Electromagnetic Induction
07.3[1 mark]

State what makes an energy resource renewable.

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A renewable resource can be replaced or regrown as fast as it is used, so it is not finite and does not run out.

1 mark

How the marks are earned

  1. Any one of: it can be replenished; it can be regrown; it will not run out. Saying it is not finite is accepted. Naming examples such as solar, saying it can be renewed or got back, saying it won't get used up or avoids finite resources, and mentioning emissions all earn nothing.
Revise Energy Resources
07.4[1 mark]

Decide if the rider-powered electricity counts as renewable or not, and justify your choice.

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Renewable: the power comes from the rider, who gets energy from food that can be regrown and replaced.

1 mark

How the marks are earned

  1. Either choice earns the mark if the reason fits. Renewable: the rider gets energy from food that can be grown again. Non-renewable: the rider's supply of energy is limited, and once tired they stop producing electricity.

Why it scores

The other route also earns the mark. A student can argue that it is non-renewable, because the rider's energy is limited and they cannot generate any more once they are tired. What matters is that the reason matches the choice.

Revise Energy Resources
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PrepWise guide: OCR B GCSE Physics Paper 3 HigherQuestion 8

Emperor penguins make extremely deep dives in the sea. Figure 11 shows one at the surface with part of its body submerged. Figure 12 models the penguin's body as a cylinder. Figure 13 gives data for the penguin's body at five depths, with depth in centimetres. Gas-filled sacs inside its body get squeezed smaller as it descends.

Figure 11
A penguin in side view, partly submerged at the surface of water, with its back above the waterline and the rest of its body below it. The water is shown as a shaded block below the waterline.
Figure 12
A penguin in side view, drawn inside a transparent cylinder lying on its side. A dimension line runs along the length of the cylinder with its length written beside it, and a second short dimension line marks the cylinder's radius with its value written beside it.
Figure 13
A table with three columns, depth in centimetres, body volume in cubic metres and body density in kilograms per cubic metre, and five rows of readings.
08.1[2 marks]

Use ideas about force to explain why an object feels more pressure the deeper it goes in the sea.

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The deeper the object, the more water lies above it, so a greater weight of water presses down on it.

A greater force acts on the same area of the object. Pressure depends on force and area:. p = F over A. So the pressure is larger.

2 marks

How the marks are earned

  1. One mark: a deeper object has a greater weight of water pressing down on it from above. A greater mass of water overhead, a larger force from above, or more particles pushing down, also earns it. Saying only more water earns nothing.
  2. One mark: that gives a larger force on the same area.
  3. Saying the water's density increases loses the first mark; the mark for more force on the same area can still be earned.

Why it scores

This earns the first mark. Pressure in a liquid comes from the weight of the column of liquid above, which grows with depth.

This earns the second mark. It links the extra weight to a bigger force over the same area.

Revise Pressure
08.2[4 marks]

A penguin dives to 400 m. Seawater density is 1020 kg/m3 and g is 10 N/kg. Find the pressure in kPa.

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Choose the equation:. pressure = depth × density × gravitational field strength

Substitute:. pressure = 400 × 1020 × 10

Work it out in pascals:. p = 4 080 000 Pa

Change to kilopascals:. pressure = 4 080 000 over 1000. pressure = 4080 kPa

4 marks

How the marks are earned

  1. One mark: choose pressure = depth × density × gravitational field strength.
  2. One mark: substitute: 400 × 1020 × 10.
  3. One mark: the pressure in pascals, 4 080 000 Pa. This alone, with no conversion, earns 3 marks.
  4. One mark: convert to kilopascals, 4080 kPa. Clear working that divides a wrong value by 1000 earns this one mark.
  5. The correct answer, 4080 kPa, on the answer line earns full marks.

Why it scores

This earns the equation mark.

The depth is in metres, the density in kg/m3 and g in N/kg, so the answer comes out in pascals with no unit changes.

400 × 1020 = 408 000, and 408 000 × 10 = 4 080 000. This earns the third mark.

1 kPa is 1000 Pa, so divide by 1000. The right answer, 4080 kPa, alone earns all 4 marks.

Revise Pressure
08.3[2 marks]

Colder water is denser. Explain how that changes your pressure answer at the same 400 m depth.

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The pressure would be higher.

The depth and g are the same, but the column of colder water above the penguin has more mass, so its weight is greater and it presses harder.

2 marks

How the marks are earned

  1. One mark: the pressure would be higher than the answer to the previous part.
  2. One mark: any one reason: a greater weight of water lies overhead; pressure scales with density; depth and g are unchanged; or the water overhead has a larger mass; or more particles push down. A reply of just more mass in each unit of volume, or just a bigger downward force, earns nothing.

Why it scores

This earns the first mark. In the equation pressure = depth × density × g, only the density has changed, and a larger density gives a larger pressure.

This earns the second mark. Pressure is proportional to density when the depth and g are fixed.

Revise Pressure
08.4[2 marks]

Figure 11 shows a penguin partly under the surface. Explain why the water gives it a net upward force.

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Pressure grows with depth, so the water pushes up on the underside of the penguin with more force than it pushes down on the upper submerged surfaces. The net result is an upward force from the water, the upthrust.

The size of the upthrust equals the weight of the water the penguin displaces.

2 marks

How the marks are earned

  1. One mark: the water's pressure on the penguin gives an upthrust, a net force upwards.
  2. One mark: the upthrust comes from the weight of the water the penguin pushes aside, or the water displaced pushes up. A net force from the water that does not include the penguin's own weight is also accepted. Naming Newton's third law earns nothing.

Why it scores

This earns the first mark. The forces from the water act on all submerged surfaces, and the larger force on the underside wins.

This earns the second mark. The upthrust comes from the water only. The penguin's own weight is a separate downward force that is not part of it.

Revise Pressure
08.5[3 marks]

Use Figure 12's radius and length, mass 25 kg, and cylinder volume = π × radius2 × length, to find density in kg/m3.

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Read from Figure 12: radius 0.1 m and length 1.2 m.. volume = π × 0.12 × 1.2. volume = 0.0377 m3

Choose the equation and substitute:. density = mass over volume. density = 25 over 0.0377

Evaluate:. density = 663 kg/m3. This is about 660 kg/m3 to 2 significant figures.

3 marks

How the marks are earned

  1. One mark: the volume, from π × radius2 × length. Any volume that rounds to 0.038 m3 is accepted, such as 0.037699 m3 or 38 000 cm3.
  2. One mark: choose density = mass ÷ volume, and use it, for example 25 ÷ 0.0377. This mark is also earned by using a wrong volume of your own.
  3. One mark: the density, 663 kg/m3, which must come from the correct volume. An answer of 660 at 2 significant figures, or 700 at 1 significant figure, is accepted.
  4. The correct answer, 663 kg/m3, on the answer line earns full marks.

Why it scores

This earns the volume mark. The radius is squared first: 0.1 × 0.1 = 0.01. Then 0.01 × 1.2 = 0.012, and 0.012 × π = 0.0377.

This earns the select-and-apply mark. Using your own volume here still earns it.

This earns the final mark. The right answer alone earns all 3 marks.

Revise Density
08.6[3 marks]

Explain the trends in Figure 13, the penguin's body volume and body density at five depths.

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As the penguin dives deeper, its body volume decreases and its body density increases.

The volume decreases because the greater pressure at depth compresses the air in the penguin's air sacs.

The density increases because the penguin's mass stays the same but occupies a smaller volume. Density depends on mass and volume:. density = mass over volume

3 marks

How the marks are earned

  1. One mark: a correct trend, any one of: as depth increases the volume falls; as depth increases the density rises; as volume falls the density rises. A wrong trend earns nothing and can cancel the explanations. Saying proportional or inversely proportional is ignored.
  2. One mark: the volume falls because the air in the air sacs is compressed.
  3. One mark: the density rises because the same mass is squeezed into a smaller volume. Repeating the trend as the reason earns nothing, for example saying the density rises because there is more mass in each unit of volume.

Why it scores

This earns the trend mark. Quote the data to be safe: the volume falls from 0.028 m3 at 72 cm to 0.021 m3 at 120 cm, while the density rises from 893 to 1190 kg/m3.

This earns the second mark. Gases can be compressed, while the rest of the body is almost incompressible.

This earns the third mark. A fixed mass divided by a smaller volume gives a larger density.

Revise Density
08.7[2 marks]

Use Figure 13 and seawater density 1020 kg/m3 to explain why the penguin sinks at 100 cm when not swimming.

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At 96 cm the penguin's density is 1087 kg/m3 and at 108 cm it is 1136 kg/m3, so at 100 cm it is about 1100 kg/m3. That is greater than the seawater's 1020 kg/m3.

So the penguin's weight is greater than the upthrust from the water, and the upthrust cannot balance it. Without swimming, nothing holds it up, so it sinks.

2 marks

How the marks are earned

  1. One mark: the penguin is denser than the seawater at that depth. Saying it is already sinking at 96 cm also earns this.
  2. One mark: its weight is greater than the upthrust from the water, so the upthrust is too small to balance the weight. Saying that swimming gives an upward force to keep its position is also accepted. Saying only that the forces are unbalanced earns nothing.

Why it scores

This earns the first mark. An object denser than the liquid around it sinks.

This earns the second mark. At 72 cm the penguin is less dense than seawater, so it floats; once it is denser, the upthrust is too small and swimming has to supply an upward force to keep its position.

Revise Density
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PrepWise guide: OCR B GCSE Physics Paper 3 HigherQuestion 9

Figure 14 shows a gas thruster, which changes a satellite's orbit by letting gas escape. At first the satellite circles Earth steadily, around 500 km up. The thruster lifts it roughly 3 km higher and is then turned off, after which the satellite settles in a new steady circular orbit.

Figure 14
A satellite drawn as a box with two flat solar panels, and a gas thruster on one side. A cloud of gas leaves the thruster's nozzle, with labels naming the gas thruster and the gases released.
09.1[1 mark]

Compare the force of gravity on the satellite in the two orbits.

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Gravity is a little stronger in the first orbit, and a little weaker in the new one, because the force gets weaker as the distance from the Earth grows.

1 mark

How the marks are earned

  1. The force of gravity is weaker in the new, higher orbit, or stronger in the original orbit. The comparison alone earns the mark; adding that the satellite is closer to the Earth in the original orbit is not needed.
Revise Orbits
09.2[2 marks]

Explain how the satellite's speed in the new orbit differs from its speed in the first orbit.

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The satellite moves more slowly in the new orbit.

This is because the new orbit has a larger radius. The pull of gravity is weaker there, so a smaller speed is enough to keep the satellite on a circular path.

2 marks

How the marks are earned

  1. One mark: the speed in the new orbit is lower. The opposite statement, that the speed was higher in the original orbit, is accepted.
  2. One mark: the orbit now has a bigger radius. Saying only that the satellite is farther away or higher up, or that the distance or height has grown, or mentioning centripetal force or the circumference of the orbit, earns nothing.

Why it scores

This earns the first mark. A stable orbit at a different height needs a different speed.

This earns the second mark. For a stable circular orbit, the larger the radius, the lower the speed. Saying only that it is further away, or that the distance has grown, is not enough.

Revise Orbits
09.3[2 marks]

Give the reason a satellite going steadily round a circle is still accelerating.

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The satellite's direction of travel keeps changing as it goes round the circle.

Velocity is speed in a given direction, so a changing direction means a changing velocity, and a changing velocity is an acceleration, even when the speed stays the same.

2 marks

How the marks are earned

  1. One mark: the direction of the satellite's motion keeps changing.
  2. One mark: so its velocity keeps changing, which means it is accelerating. Saying the velocity increases or decreases, or only mentioning gravity or speed, earns nothing.

Why it scores

This earns the first mark. Moving in a circle means turning all the time.

This earns the second mark. Acceleration is a change in velocity, not only a change in speed.

Revise Orbits
09.4[3 marks]

The satellite's momentum is 9 144 000 kg m/s and its mass is 1200 kg. Find its velocity in m/s.

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Rearrange for the velocity:. momentum = mass × velocity. velocity = momentum over mass

Substitute:. velocity = 9 144 000 over 1200

Work it out:. v = 7620 m/s

3 marks

How the marks are earned

  1. One mark: choose momentum = mass × velocity. A correct substitution also earns this mark.
  2. One mark: rearrange and substitute: velocity = 9 144 000 ÷ 1200.
  3. One mark: the velocity, 7620 m/s.
  4. The correct answer, 7620 m/s, on the answer line earns full marks.

Why it scores

This earns the equation mark. It needs rearranging to make the velocity the subject.

This earns the substitution mark.

9 144 000 ÷ 1200 = 7620. The right answer alone earns all 3 marks.

Revise Momentum
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END OF QUESTIONS90 marks total
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