4.6Chapter 4: Electricity

Chapter 4 Review: Electricity — Alhussan Physics - Stage 7 Revision Notes & Topical Questions

5 min read 7 parts Lesson 6 of 6 1 quiz

📚 Alhussan Physics - Stage 7 Hub / Topical Revision

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4.6 Chapter 4 Review: Electricity — Alhussan International Academy — Physics (Stages 7–9) notes: Revise static charge, current, series circuits, circuit models, two-way switches and electrical safety.Charging — rubbing a balloon on a jumper transfers electrons from the jumper to …

Sticking to a wall
Conservation
Insulators and conductors
Chain of changes
Net charge
Resistance

Section 1 of 7Static charge and the sticking balloon

1Charging

Charging rubbing a balloon on a jumper transfers electrons from the jumper to the balloon, so the balloon has a net negative charge.

2Sticking to a wall

Sticking to a wall the wall is an insulator and neutral overall.
The negative charge on the balloon repels the electrons in the wall's surface away, leaving the surface slightly positive.
The balloon is attracted to this positive surface, and the attraction is enough to hold it up.

3Conservation

Conservation charge is conserved, so when the balloon gains electrons the jumper loses the same amount.

4Insulators and conductors

Insulators and conductors insulated objects keep a charge, but conductors let it flow away.

Section 2 of 7Current, resistance and measuring

Current

Current the flow of charge, measured in amperes with an ammeter connected in series.

Series circuit

Series circuit adding lamps increases the resistance and reduces the current, while adding cells increases the current.
The same current passes through every component, and a switch must be closed for any current to flow.

Conductors

Conductors metals and graphite let charge flow.

Insulators

Insulators plastic, wood and glass do not.

Section 3 of 7Models of circuits

Models

Models a circuit can be modelled with a loop of rope or as trucks delivering food to a supermarket.
The battery or pusher drives the flow, the loop carries it round, and energy is delivered where it is needed.

Limits

Limits all models have limits and should be tested against evidence.
A model with limits is not wrong, and it should be judged by one strength and one limit.

Section 4 of 7Two-way switches

Use

Use some circuits use two switches to control one lamp, such as a staircase light.

Operation

Operation one switch can be flipped between connections 1 and 3, and the other between connections 2 and 4.
The lamp is on only when the two switches connect to form a complete loop through the cell.
Flipping either switch changes this, so the light can be switched on or off from either place.

Section 5 of 7Cause and effect in circuits

Chain of changes
- a change in one factor starts a chain of responses.
- Adding a lamp raises the resistance, which lowers the current, which makes each lamp dimmer.

Idea	Key fact
Static charge	Rubbing transfers electrons; like charges repel, unlike attract
Current	Flow of charge, measured in A with an ammeter in series
Conductors	Metals and graphite let charge flow
Insulators	Plastic, wood and glass keep charge in place
Series circuit	More lamps means more resistance and less current
Safety	Earthing lets charge flow safely to the ground

Section 6 of 7Key terms

Term	Meaning
Electron	a tiny negatively charged particle that moves in a circuit.
Net charge	the overall charge on an object.
Resistance	how much a component opposes the flow of charge.
Switch	a component that opens or closes a circuit.
Model	a simplified representation used to explain and predict.

Section 7 of 7Exam technique

Thinking the wall is charged — it is neutral overall, and its surface is affected by the balloon's charge.

Mixing up series and parallel effects of adding lamps — in series, more lamps reduce the current.

Forgetting that only electrons move in solid conductors — protons stay in the nuclei.

Thinking a model is wrong because it has limits — all models have limits.

Last updated: 13 October 2026