Magnets, magnetic fields and electromagnetism – GCSE Physics exam questions with mark scheme

1Grade 1–33 marks

(a) Describe the difference between a permanent magnet and an induced magnet. [2]

(b) Name one magnetic material. [1]

(a) a permanent magnet produces its own magnetic field (allow: is always magnetic / keeps its magnetism)(1)
(a) an induced magnet only becomes a magnet when placed in a magnetic field (and loses most/all of its magnetism quickly when removed)(1)
(b) any one from: iron / steel / cobalt / nickel (reject: 'metal' alone, aluminium, copper)(1)
Answer: (a) A permanent magnet has its own field; an induced magnet is only magnetic while in a magnetic field. (b) e.g. iron
Examiner tip: Aluminium and copper are metals but they are NOT magnetic materials.

2Grade 4–54 marks

A long straight wire carries a direct current.

(a) Describe the shape of the magnetic field around the wire. [1]

(b) Give two factors that affect the strength of the magnetic field at a point near the wire. [2]

(a) concentric circles centred on the wire (allow: circles around the wire; ignore 'in a plane at right angles to the wire')(1)
(b) the size of the current (allow: greater current gives stronger field)(1)
(b) the distance from the wire (allow: closer to the wire gives stronger field)(1)
(c) reverse the direction of the current(1)
Answer: (a) concentric circles around the wire (b) size of the current; distance from the wire (c) reverse the current
Examiner tip: Field strength depends on the current AND the distance from the wire — give both.

3Grade 1–3Foundation4 marks

The diagram shows two identical ring magnets on a wooden rod. The upper ring magnet floats above the lower ring magnet without touching it.

(a) What does this tell you about the poles of the two magnets that are facing each other? [1]

(b) The force between the two magnets is a non-contact force. What is meant by a non-contact force? [1]

(c) The upper ring magnet is lifted off the rod, turned upside down and put back on the rod. Describe what happens to the upper ring magnet. [1]

(d) Suggest why the rod is made of wood and not steel. [1]

(a) they are like poles / the same poles allow north faces north or south faces south; like poles repel(1)
(b) a force that acts between objects that are not touching / that are separated allow a force that acts at a distance(1)
(c) it moves down (onto the lower magnet) / it is attracted to the lower magnet / the gap closes allow it sticks to the lower magnet; ignore reasons(1)
(d) steel is a magnetic material so the magnets would be attracted to the rod allow the magnets would stick to / be pulled against the rod; allow the rod would become magnetised; do not accept 'steel is a magnet'(1)
Answer: (a) Like poles (they repel). (b) A force between objects that are not touching. (c) It is attracted down onto the lower magnet. (d) Steel is magnetic, so the magnets would be attracted to the rod.
Examiner tip: In (c) turning the magnet over changes like poles to unlike poles, so the repulsion becomes attraction — say what the magnet does, not just 'it attracts'.

4Grade 1–3Foundation4 marks

A student holds a permanent bar magnet vertically. She hangs a steel paper clip from the bottom of the magnet. She then hangs a second steel paper clip from the bottom of the first clip, so the clips form a chain.

(a) Explain why the second paper clip is held by the first paper clip, even though the first clip is not a permanent magnet. [2]

(b) The student carefully pulls the top paper clip away from the magnet, holding only the top clip. The second clip falls off almost straight away. Explain why. [1]

(c) At a recycling centre, a large magnet is used to separate steel cans from aluminium cans. Which cans does the magnet pick up? Give a reason for your answer. [1]

(a) the first clip becomes an induced magnet (because it is in the magnetic field of the bar magnet) allow the first clip is magnetised by the magnet(1)
(a) (the second clip is a magnetic material so) the first clip attracts the second clip allow the second clip also becomes an induced magnet and they attract; ignore 'they stick together'(1)
(b) the first clip loses its (induced) magnetism (quickly) when it is removed from the magnetic field allow it is no longer an (induced) magnet so it cannot attract the second clip(1)
(c) steel cans and steel is a magnetic material / contains iron (aluminium is not magnetic) both parts needed for the mark(1)
Answer: (a) The first clip is in the magnet's field so becomes an induced magnet, which attracts the second clip. (b) Out of the field the induced magnetism is quickly lost. (c) Steel cans, because steel is a magnetic material (aluminium is not).
Examiner tip: Use the phrase 'induced magnet' — 'the magnetism passes down the chain' does not get the first mark.

5Grade 4–55 marks

The diagram shows a bar magnet and two positions, labelled B and C, where a plotting compass can be placed.

(a) Describe how a student could use a plotting compass to draw one magnetic field line that starts near the north pole of the magnet. [3]

(b) In which direction does the compass needle point when the compass is at position B? [1]

(a) place the compass near the north pole and mark (with a dot) the position the needle points to allow mark both ends of the needle(1)
(a) move the compass so that the tail of the needle is over / at the last dot and mark the new position the needle points to; repeat allow move the compass along in the direction the needle points and mark again(1)
(a) (continue until the compass reaches the south pole, then) join the dots with a smooth curve and add an arrow (pointing from N to S) allow join the dots to make the field line(1)
(b) to the right / towards the south pole end / parallel to the magnet from N to S allow →; do not accept towards the north pole(1)
(c) to the left / towards the magnet / towards the south pole allow ←; do not accept away from the magnet(1)
Answer: (a) Mark where the needle points, move the compass so its tail is on that mark, repeat to the S pole, then join the dots and add an arrow from N to S. (b) To the right (N to S). (c) To the left, towards the S pole.
Examiner tip: A compass needle points along the field, i.e. away from a north pole and towards a south pole — at C it points back towards the magnet.

6Grade 4–55 marks

A walker uses a magnetic compass to find north.

(a) A compass needle is a small magnet. Away from any magnets, the needle always settles pointing in the same direction.

Explain what this tells us about the Earth. [2]

(b) When the walker stands next to a steel gate, the compass needle points in a different direction. Suggest why. [1]

(i) State where the magnetic field of a bar magnet is strongest. [1]

(ii) How is this shown on a diagram of the magnet's field lines? [1]

(a) the Earth has (its own) magnetic field allow the Earth behaves like a (bar) magnet; allow the needle lines up with the Earth's magnetic field(1)
(a) (so) the Earth's core must be magnetic allow there is a magnet inside the Earth; do not accept the North Pole is magnetic without reference to the inside / core(1)
(b) the steel (gate) is magnetic / is magnetised / has become an induced magnet, so it changes the magnetic field at the compass allow the gate attracts the needle; do not accept 'the gate is metal' alone(1)
(c)(i) at the poles allow at the ends (of the magnet)(1)
(c)(ii) the field lines are closest together (at the poles) allow the lines are most concentrated / most dense there(1)
Answer: (a) The Earth has a magnetic field, so its core must be magnetic. (b) The steel gate is magnetic/magnetised and changes the field at the compass. (c)(i) At the poles. (ii) The field lines are closest together there.
Examiner tip: 'The gate is metal' scores nothing — say it is a magnetic material (steel), because aluminium or copper gates would have no effect.

7Grade 6–7Higher5 marks

A student investigates the magnetic field around a long straight wire. The wire carries a constant current of 5.0 A.

She uses a magnetic field sensor to measure the field strength at different distances from the wire. Before switching on the current, she sets the sensor reading to zero.

Her results are shown in the table.

Distance from wire in cm	1.0	2.0	3.0	4.0	5.0
Magnetic field strength in μT	100	50	33	25	20

(a) Describe the relationship between the distance from the wire and the magnetic field strength. Use data from the table in your answer. [2]

(b) Predict the magnetic field strength 8.0 cm from the wire. [1]

The current is reduced to 3.0 A. Calculate the magnetic field strength 2.0 cm from the wire. [1]

(d) Suggest why the student set the sensor reading to zero before switching on the current. [1]

(a) as the distance increases the field strength decreases allow the further away, the weaker the field(1)
(a) (field strength is inversely proportional to distance:) doubling the distance halves the field strength, with a correct data example, e.g. 1.0 cm → 2.0 cm, 100 μT → 50 μT allow distance × field strength is constant (= 100) with data; a correct example is needed for this mark(1)
(b) 12.5 μT allow 12–13 μT(1)
(c) 30 μT allow 50 × 3.0 ÷ 5.0 = 30 for the mark(1)
(d) to remove the effect of the Earth's magnetic field (so only the field due to the current is measured) allow to cancel the background / other magnetic fields; ignore 'to make it accurate' alone(1)
Answer: (a) Field strength decreases as distance increases; it is inversely proportional — doubling distance (1.0→2.0 cm) halves it (100→50 μT). (b) 12.5 μT (c) 30 μT (d) To remove the effect of the Earth's (background) magnetic field.
Examiner tip: 'Inversely proportional' only earns credit when backed by numbers — quote a pair where distance doubles and field halves.

8Grade 6–76 marks

A student makes an electromagnet by winding insulated wire around an iron nail and connecting it to a low-voltage d.c. power supply.

She wants to investigate how the number of turns of wire on the nail affects the strength of the electromagnet.

Describe a method the student could use. Include how she would make sure that it is a fair test. [6]

wind a set number of turns (e.g. 10) of insulated wire around the iron nail / core(1)
connect the coil in series with an ammeter (and a variable resistor) to the d.c. supply(1)
switch on and measure the strength by counting the number of (identical) paper clips the electromagnet can pick up allow mass of iron filings / reading on a balance when a steel block is attracted / force on a newtonmeter(1)
increase the number of turns in steps (e.g. 10, 20, 30, 40, 50) and repeat the measurement for each(1)
keep the current the same for every number of turns, using the ammeter to check and the variable resistor to adjust it(1)
(adding turns adds wire, increasing the resistance, so without adjustment the current would decrease)(1)
use the same nail / core, the same type of wire and the same (size and type of) paper clips(1)
repeat each reading and calculate a mean(1)
switch off between readings so the wire does not overheat (and burn the student / change its resistance)(1)
plot a graph of number of paper clips (strength) against number of turns(1)

Level	Marks	What it looks like
Level 3	5–6	A coherent, logically ordered method that could be followed to get valid results. It states how strength is measured, that the number of turns is changed in steps, and explains how the current is kept constant (with an ammeter and variable resistor), with other control variables and repeats.
Level 2	3–4	A method with the main steps present: changing the number of turns and measuring strength in a stated way. At least one relevant control variable is given, but some detail or the reason for controlling the current may be missing.
Level 1	1–2	Some relevant steps, e.g. 'add more coils and see how many paper clips it picks up', with little detail on control variables. The method may not be in a logical order.
0	0	No relevant content.

Answer: Wind 10 turns of insulated wire on the nail, connect in series with an ammeter and variable resistor to a low-voltage d.c. supply. Switch on and count how many identical paper clips the nail picks up. Repeat for 20, 30, 40, 50 turns. Keep the current constant (adjusting the variable resistor, since more wire means more resistance), use the same nail and clips, repeat each reading and take a mean, switch off between readings to stop the wire heating, then plot clips against turns.
Examiner tip: Top-band answers notice that adding turns adds wire and so resistance — the current must be measured and kept the same, or the test is not fair.

9Grade 6–7Triple only6 marks

The diagram shows a relay used in a car. When the driver closes switch S, the starter motor turns.

The starter motor needs a very large current. The current in the circuit with switch S is small.

(a) Explain how closing switch S makes the starter motor turn. [4]

(b) Suggest why the core of the coil is made of iron. [1]

(a) there is a current in the coil (so it produces a magnetic field) allow the coil becomes an electromagnet(1)
(a) the iron core is magnetised / becomes an (induced) magnet, making the magnetic field stronger allow the core becomes an electromagnet(1)
(a) the (iron) armature is attracted (down) towards the core allow pulled down; ignore 'the spring' unless incorrect(1)
(a) the armature pivots and pushes the contacts together, completing the starter motor circuit (so there is a current in the motor) allow closes the contacts / switches on the motor circuit(1)
(b) any one from: iron is easily magnetised / makes the magnetic field much stronger (so the small current can attract the armature); iron loses its magnetism (quickly) when the current is switched off (so the armature is released and the motor stops) allow iron is easily magnetised and demagnetised(1)
(c) the switch / wires to the driver only carry a small current (so they can be thinner / are safer / the switch does not spark or overheat) allow the high-current circuit is kept separate from the driver; ignore 'it is safer' alone(1)
Answer: (a) Current in the coil magnetises the iron core; the iron armature is attracted to the core, pivots and closes the contacts, completing the motor circuit. (b) Iron is easily magnetised (making the field stronger) and loses its magnetism quickly when the current stops (either reason). (c) The driver's switch and wiring only carry a small current, so can be thin and are safer.
Examiner tip: In 'interpret a device' questions, follow the sequence: current → magnetic field → armature attracted → contacts close → second circuit switched on. Missing a link loses a mark.

10Grade 8–9Higher6 marks

The diagram shows a solenoid. When viewed from end X, the current in the coil flows anticlockwise.

(a) State which end of the solenoid, X or Y, is a north pole. [1]

(b) Describe the magnetic field inside the solenoid. [2]

(c) A scrapyard uses a large electromagnet on a crane to lift old cars. The electromagnet is a solenoid with an iron core. An engineer suggests replacing the iron core with a steel core.

Explain why a steel core would be unsuitable. [2]

(d) The current in the scrapyard electromagnet is reversed. Explain what happens to the force on a car. [1]

(a) X(1)
(b) strong allow stronger than outside the solenoid(1)
(b) uniform / the same strength (and direction) everywhere inside allow field lines parallel and equally spaced; ignore 'straight' alone(1)
(c) steel would become permanently magnetised / stays magnetised when the current is switched off allow steel keeps its magnetism / becomes a permanent magnet(1)
(c) so the cars would not be released / dropped when the current is switched off(1)
(d) it is still attracted (with the same size force) because the car is a magnetic material / an induced magnet, so the force on it is always attractive do not accept the car is repelled; reason needed(1)
Answer: (a) X (b) Strong and uniform. (c) Steel would stay magnetised when switched off, so the cars would not drop. (d) The car is still attracted — the force on a magnetic material is always attractive (the car's induced poles also reverse).
Examiner tip: In (d) many students say 'repelled'. Reversing the current reverses the induced poles in the car too, so the force stays attractive.

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