Series & Parallel Circuits

PhysicsAQAGCSEUnit: Electricity
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The basics

Christmas Lights vs House Lights

⚡ Christmas Lights vs House Lights

Old-fashioned Christmas lights were wired in series — if ONE bulb blew, the WHOLE string went dark! You'd have to test every single bulb to find the culprit. Modern lights and house circuits use parallel wiring — each bulb has its own path to the power. One blows? The others stay lit. This isn't just convenient; it's physics. Series and parallel circuits follow completely different rules for current, voltage, and resistance. Mix them up in an exam and you'll lose serious marks!
Spotlight
Series Circuits — One Path Only

What it looks like: All components connected in a single loop — current has only ONE path to follow.

Exam tip

Earn the mark scheme marks

🧠 Memory Aid

Series vs Parallel rules — "SVSS / PVSS":

Series: Same current, Voltages sum, Sum of resistances.

Parallel: Same voltage, Currents sum, Smaller total resistance.

Christmas lights trick:

Old fairy lights = series (one breaks, all go dark). Modern house lights = parallel (one breaks, rest stay on). Match the circuit type to this real-world example to remember which rule applies.

Parallel resistance check — "Always Less":

Parallel total resistance is ALWAYS less than the smallest resistor in the group. If your answer is bigger — it's wrong. No exceptions.

Now try it yourself

Quiz · Question 1 of 20

In a series circuit, what is true about the current at all points?

Tap an answer to check it

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