Exam Tips for Resistance and Ohm's Law
Part of Resistance & Ohm's Law — GCSE Physics
This exam tips covers Exam Tips for Resistance and Ohm's Law within Resistance & Ohm's Law for GCSE Physics. Revise Resistance & Ohm's Law in Electricity for GCSE Physics with 14 exam-style questions and 30 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 15 of 16 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
Topic position
Section 15 of 16
Practice
14 questions
Recall
30 flashcards
💡 Exam Tips for Resistance and Ohm's Law
🎯 Common Question Types:
- Ohm's Law calculation: V = IR or R = V/I (2 marks)
- Describe V-I graph shape for filament lamp (2 marks)
- Explain why resistance changes with temperature (3 marks)
- Required practical: method and control variables (4 marks)
- State and explain how a thermistor/LDR works (2 marks)
📝 Key Command Words:
- Calculate — show V = IR substitution with units
- Describe — say what the graph looks like (shape, gradient)
- Explain — say why (use "because" with ion vibration)
- Sketch — draw a labelled graph (axes, origin, shape)
⚠️ Common Mistakes to Avoid:
- Forgetting units for resistance (Ω, not R)
- Saying metal resistance decreases with temperature — it increases
- Confusing thermistor (less R when hot) with metal wires (more R when hot)
- Drawing filament lamp V-I graph as a straight line — it curves
- Not turning off the power supply between readings in required practical
Quick Check: A thermistor is placed in ice water, then hot water. What happens to its resistance, and how does this affect current in the circuit?
In ice water: resistance is high, so current is low. In hot water: resistance decreases, so current increases. Thermistors have resistance that decreases as temperature increases.