Year 8 Electricity and Magnetism Worksheet - Intermediate

Year 8 Electricity and Magnetism worksheet for Year 8 (Key Stage 3 / Year 7-9 (Ages 11-14)). Intermediate level science practice, aligned to the UK National Curriculum. Print-ready with answer key included.

Science•Key Stage 3 / Year 7-9 (Ages 11-14)•Electricityintermediate

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Electricity and Magnetism: Circuits, Charge and Fields

Year 8 | Ages 12–13 | Intermediate

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Instructions: Work through each activity, showing your calculations and explaining your scientific reasoning where asked. Use the data and circuit descriptions provided; all answers can be written in the boxes.

Current, Voltage and Resistance

Use the relationship V = I × R, where V is voltage in volts (V), I is current in amperes (A) and R is resistance in ohms (Ω). Rearrange the relationship when needed. Show your working and include the correct unit.

1. A 6 V battery is connected across a 3 Ω resistor. Calculate the current. [2 marks]

2. A current of 0.5 A flows through a 12 Ω resistor. Calculate the voltage across it. [2 marks]

3. A 9 V supply produces a current of 0.3 A through a component. Calculate the component’s resistance. [2 marks]

4. A lamp has a resistance of 8 Ω and a current of 0.25 A. Calculate the voltage across the lamp. [2 marks]

Series and Parallel Circuits

Use the circuit facts in each question. In a series circuit, current is the same at every point and component voltages add to the supply voltage. In a parallel circuit, the voltage across each branch is the supply voltage, and the branch currents add to the total current.

1. Two lamps are connected in series to a 12 V supply. The first lamp has a voltage of 5 V across it. What is the voltage across the second lamp? [2 marks]

2. A 0.4 A current flows through a series circuit containing a battery and two lamps. What current flows through the second lamp? [1 mark]

3. Two branches are connected in parallel to a 6 V battery. What is the voltage across each branch? [1 mark]

4. The two branches of a parallel circuit carry currents of 0.2 A and 0.35 A. Calculate the total current from the battery. [2 marks]

Choosing and Reading Circuit Meters

For each situation, name the correct meter and state how it should be connected. An ammeter measures current and is connected in series. A voltmeter measures the potential difference across a component and is connected in parallel.

1. Which meter measures the current through a lamp, and how should it be connected? [2 marks]

2. Which meter measures the potential difference across a resistor, and how should it be connected? [2 marks]

3. An ammeter in series with a component reads 0.18 A. What current does the ammeter show? [1 mark]

4. A voltmeter connected in parallel across a cell reads 1.5 V. What potential difference does it show? [1 mark]

Static Electricity: Charge and Forces

Apply the model of electrons transferring between materials. An object that gains electrons becomes negatively charged; an object that loses electrons becomes positively charged. Remember that like charges repel and opposite charges attract.

1. A plastic rod gains electrons when rubbed with a cloth. What charge does the rod acquire? [1 mark]

2. A balloon loses electrons during rubbing. What charge does the balloon acquire? [1 mark]

3. Two objects are both negatively charged. Do they attract or repel? [1 mark]

4. A positively charged object is brought near a negatively charged object. Do they attract or repel? [1 mark]

Magnets, Fields and Electromagnets

Answer using the ideas that magnetic field lines show the direction a north pole would move, and that a stronger electromagnet can be made by increasing the current or adding more turns of wire around the core. Use complete scientific statements where appropriate.

1. Where is the magnetic field strongest around a bar magnet: where the field lines are closest together or furthest apart? [1 mark]

2. Outside a bar magnet, in which direction do magnetic field lines go: from north to south or from south to north? [1 mark]

3. State one change that would make an electromagnet stronger. [1 mark]

4. A current-carrying coil is wrapped around an iron core. What happens to the core’s magnetism when the current is switched off? [1 mark]

Answer Key

Activity 1: 2 A ; 6 V ; 30 Ω ; 2 V

Activity 2: 7 V ; 0.4 A ; 6 V across each branch ; 0.55 A

Activity 3: Ammeter, in series ; Voltmeter, in parallel across the resistor ; 0.18 A ; 1.5 V

Activity 4: Negative ; Positive ; Repel ; Attract

Activity 5: Where the field lines are closest together ; From north to south ; Increase the current or increase the number of turns of wire ; The core loses its magnetism (or becomes much less magnetic).