Year 9 Science · Unit 3 · Lesson 18

Series and Parallel Circuits

Foundation Worksheet

Name

Date

Class

Learning Goals

Identify whether a circuit is series or parallel based on its characteristics.
Describe the behaviour of voltage and current in series and parallel circuits.
Explain why Australian home wiring uses parallel circuits.

Warm Up

Sort it!

Write each statement from the pool into the correct category box. Some statements belong to "Both" circuit types.

All components get the same voltage If one bulb fails, all go out Current is the same throughout Used in Australian home wiring Components connect end-to-end in one loop Each branch has full battery voltage Needs a complete path to work One branch fails → others keep working Old-style Christmas lights Adding components increases total resistance

Series Circuit

Parallel Circuit

Both

Your Turn

Match each term to its definition

Write the letter of the correct definition next to each circuit characteristic. Then write a brief reason in the justification column.

Circuit characteristic	Answer	Justification (why?)
Voltage behaviour in series
Current behaviour in series
Effect of one component failing in parallel
How total resistance is added in series
Typical real-world use of parallel
Switch control in parallel

Definition bank:

A. Voltage is divided among components B. Current is identical at every point C. Other branches continue to work D. R_total = R₁ + R₂ + R₃ (resistance adds up) E. Australian home wiring, each appliance gets full 240 V F. Each appliance can be switched on/off independently

Show What You Know

1. Explain why old-style Christmas lights (wired in series) all went out when one bulb failed, but modern house lights (wired in parallel) stay on when one globe blows.

Recall 2 marks

2. In a parallel circuit, what happens to the voltage across each branch when a new branch is added? What happens to the total current from the battery?

Recall 2 marks

Wrap Up

In one sentence, what was the main idea of this lesson?