Series & Parallel Circuits

Year 7
Physics · Electricity · Interactive Lesson

🎯 Learning Objectives

1
Recognise and describe the differences between series and parallel circuits
2
Describe how switches and components affect series and parallel circuits
3
Explain why current behaves differently around series and parallel circuits

➰ Series Circuit

All components are connected in one big loop. Current has only one path to follow.

⚠️ If one bulb breaks, the circuit is broken and all bulbs go out.

🔀 Parallel Circuit

Components are in separate branches. Current has multiple paths to choose from.

✅ If one bulb breaks, other branches stay lit. Used in home wiring!

📊 Comparing Circuit Types

FeatureSeries CircuitParallel Circuit
Path for currentOne single loopMultiple branches
Current (amps)Same everywhereSplits at each junction
If one bulb breaksAll go outOthers stay on
Switch effectControls whole circuitCan control individual branches
Used in homes?RarelyYes — all home wiring
Brightness with more bulbsDimmer (resistance increases)Same (each branch independent)

⚡ Current in Parallel Circuits

In a parallel circuit, current splits when it reaches a junction where the wire divides into branches.


When branches rejoin, the currents add back together.


Total current = Sum of all branch currents
0.6 A total → 0.3 A + 0.3 A in two equal branches
Main wire current
0.6 A
↓ splits
Branch 1
0.3 A
Branch 2
0.3 A

Series Circuit Simulator

Circuit Status
COMPLETE ✅

Current flows through every component in one loop.

Current Readings
At Battery0.60 A
After Bulb 10.60 A
After Bulb 20.60 A

In series: current is the same at every point.

Controls

Bulbs: 2 — circuit has 2 bulbs in series.

🧪 Try This

1. Open the switch — what happens to ALL bulbs?

2. Add a 3rd bulb — do they get brighter or dimmer?

3. Close the switch again and observe.

Parallel Circuit Simulator

Circuit Status
BOTH ON ✅
Ammeter Readings
Main (battery)0.60 A
Branch 1 (Bulb A)0.30 A
Branch 2 (Bulb B)0.30 A

Current splits at junctions. Main = branch totals.

Branch Switches
🧪 Try This

1. Turn off Switch A — does bulb B stay on?

2. Turn off both switches — what happens?

3. Turn Switch A back on only — observe current splitting.

Switch Challenge Circuit

Battery → 3 parallel branches (A, B, C), each with its own switch

Challenge 1 of 4
Light up Bulb A only
Switch Controls
A: Open B: Open C: Open
💡 Hint

To light only one bulb, close only that bulb's branch switch.

📝 Knowledge Check

Test what you've learned about series and parallel circuits. 8 questions total.