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Magnetism and electromagnetism: GCSE questions with answers

23 physics questions on magnetism and electromagnetism. Pick your answer, then tap to see if you were right and why. Every answer comes from the Show Working science bank, checked against the GCSE content every board in England teaches.

Quiz yourself: 23 questions 2 6-mark questions

01 / Quiz yourselfTry it, then tap to check

Magnetism and electromagnetism questions to try

Choose your answer before you open it. Then read why, so it sticks.

01 / Magnetism and electromagnetismBoth tiers

The north pole of one magnet is brought near the north pole of another. What happens?

  1. ANothing happens
  2. BThey repel
  3. CThey attract
  4. DBoth magnets lose their magnetism
Show the answer

Answer: B They repel

Like poles (north and north, or south and south) repel each other. Unlike poles (north and south) attract. These forces act without the magnets touching, so they are non-contact forces.

Checked against AQA GCSE Physics 8463 specification, 4.7.1.1 Poles of a magnet

02 / Magnetism and electromagnetismBoth tiers

What is an induced magnet?

  1. AA magnet made only from copper
  2. BA material that becomes a magnet when placed in a magnetic field
  3. CA magnet that makes its own field all the time
  4. DA magnet that only ever repels
Show the answer

Answer: B A material that becomes a magnet when placed in a magnetic field

A permanent magnet makes its own magnetic field. An induced magnet only becomes a magnet while it is in a magnetic field, and loses most or all of its magnetism quickly when taken out. Induced magnetism always causes attraction.

Checked against AQA GCSE Physics 8463 specification, 4.7.1.1 Poles of a magnet

03 / Magnetism and electromagnetismBoth tiers

How can you tell that an object is a permanent magnet, not just a magnetic material?

  1. AIt attracts one pole of another magnet
  2. BIt conducts electricity
  3. CIt is made of metal
  4. DIt repels one pole of another magnet
Show the answer

Answer: D It repels one pole of another magnet

Iron, steel, cobalt and nickel are magnetic materials: a magnet attracts them. Attraction alone does not prove an object is a magnet, because magnets attract magnetic materials too. Only repulsion shows it is a magnet. Aluminium and copper are not magnetic.

Checked against AQA GCSE Physics 8463 specification, 4.7.1.2 Magnetic fields

04 / Magnetism and electromagnetismBoth tiers

Outside a bar magnet, which way do the magnetic field lines point?

  1. AFrom the south pole to the north pole
  2. BFrom the north pole to the south pole
  3. COut from the middle to both poles
  4. DIn from both poles to the middle
Show the answer

Answer: B From the north pole to the south pole

The direction of a magnetic field is the direction of the force on a north pole placed in it. So outside a magnet the field lines go from the north pole to the south pole. Field lines never cross.

Checked against AQA GCSE Physics 8463 specification, 4.7.1.2 Magnetic fields

05 / Magnetism and electromagnetismBoth tiers

Where is the magnetic field of a bar magnet strongest?

  1. AIn the middle of the magnet
  2. BAt the poles
  3. CThe same everywhere around it
  4. DFar away from the magnet
Show the answer

Answer: B At the poles

A magnetic field is strongest at the poles and gets weaker further from the magnet. On a diagram, lines closer together mean a stronger field. A plotting compass lines up with the field, so moving it around a magnet traces the field lines.

Checked against AQA GCSE Physics 8463 specification, 4.7.1.2 Magnetic fields

06 / Magnetism and electromagnetismBoth tiers

Why does a compass needle point north when no magnet is nearby?

  1. AIt lines up with the Earth’s magnetic field
  2. BGravity pulls it towards the North Pole
  3. CThe Earth’s spin pushes it round
  4. DIt points away from the Sun
Show the answer

Answer: A It lines up with the Earth’s magnetic field

A compass needle is a small bar magnet that lines up with any magnetic field. Away from other magnets it lines up with the Earth’s magnetic field and points north. This is evidence that the Earth has a magnetic field coming from its core.

Checked against AQA GCSE Physics 8463 specification, 4.7.1.2 Magnetic fields

07 / Magnetism and electromagnetismBoth tiers

How can you show that a current in a wire makes a magnetic field?

  1. AWeigh the wire with and without the current
  2. BPut a compass by the wire and see it turn when current flows
  3. CConnect a voltmeter across the wire
  4. DMeasure the temperature of the wire
Show the answer

Answer: B Put a compass by the wire and see it turn when current flows

A current in a wire makes a magnetic field around it, which turns a nearby compass. The field lines are circles around the wire, and their direction depends on the direction of the current: reverse the current and the field reverses.

Checked against AQA GCSE Physics 8463 specification, 4.7.2.1 Electromagnetism

08 / Magnetism and electromagnetismBoth tiers

How does the magnetic field around a wire change as you move further from the wire?

  1. AIt gets stronger
  2. BIt reverses direction
  3. CIt stays the same
  4. DIt gets weaker
Show the answer

Answer: D It gets weaker

The strength of the magnetic field around a wire depends on the current and the distance from the wire. A bigger current gives a stronger field, and the field gets weaker further from the wire.

Checked against AQA GCSE Physics 8463 specification, 4.7.2.1 Electromagnetism

09 / Magnetism and electromagnetismBoth tiers

Why does coiling a wire into a solenoid make a stronger magnetic field?

  1. AThe coil heats up and becomes magnetic
  2. BThe coil stores extra charge
  3. CThe longer wire carries a bigger current
  4. DThe fields from each turn add together inside the coil
Show the answer

Answer: D The fields from each turn add together inside the coil

In a solenoid the fields from all the turns add together, making a strong, uniform field inside. Outside, the field has the same shape as a bar magnet’s, with a north pole at one end and a south pole at the other.

Checked against AQA GCSE Physics 8463 specification, 4.7.2.1 Electromagnetism

10 / Magnetism and electromagnetismBoth tiers

How can you make a solenoid’s magnetic field stronger without changing the current?

  1. APut an iron core inside it
  2. BPut a copper core inside it
  3. CPut a plastic core inside it
  4. DUse fewer turns of wire
Show the answer

Answer: A Put an iron core inside it

An electromagnet is a solenoid with an iron core. The iron is easily magnetised and makes the field much stronger; more turns or a bigger current also help. Because it only works while a current flows, it can be switched on and off.

Checked against AQA GCSE Physics 8463 specification, 4.7.2.1 Electromagnetism

11 / Magnetism and electromagnetismHigher only

What is the motor effect?

  1. AA wire turning into a permanent magnet
  2. BA current made in a wire moving in a magnetic field
  3. CA magnet heating a wire near it
  4. DA force on a wire carrying a current in a magnetic field
Show the answer

Answer: D A force on a wire carrying a current in a magnetic field

When a wire carrying a current is in a magnetic field, the magnet and the wire exert a force on each other: this is the motor effect. The forces are equal in size and opposite in direction. It comes from the interaction of the two magnetic fields.

Checked against AQA GCSE Physics 8463 specification, 4.7.2.2 Fleming’s left-hand rule (HT)

12 / Magnetism and electromagnetismHigher only

In Fleming’s left-hand rule, what does the first finger point along?

  1. AThe magnetic field
  2. BThe force
  3. CThe current
  4. DThe motion of the wire
Show the answer

Answer: A The magnetic field

Hold the thumb, first finger and second finger of your left hand at right angles. The first finger points along the field (north to south), the second finger along the current (conventional current, from + to −), and the thumb gives the direction of the force (the motion).

Checked against AQA GCSE Physics 8463 specification, 4.7.2.2 Fleming’s left-hand rule (HT)

13 / Magnetism and electromagnetismHigher only

In the motor effect, the current is reversed. What happens to the force on the wire?

  1. AIt reverses direction
  2. BIt disappears
  3. CIt stays the same
  4. DIt doubles
Show the answer

Answer: A It reverses direction

Reversing either the current or the magnetic field reverses the force, as Fleming’s left-hand rule shows. Reversing both at once reverses it twice, so the force ends up in the same direction as before.

Checked against AQA GCSE Physics 8463 specification, 4.7.2.2 Fleming’s left-hand rule (HT)

14 / Magnetism and electromagnetismHigher only

What is the unit of magnetic flux density?

  1. ATesla (T)
  2. BOhm (Ω)
  3. CNewton (N)
  4. DAmpere (A)
Show the answer

Answer: A Tesla (T)

For a wire at right angles to a magnetic field, force = magnetic flux density × current × length (F = B I l), with B in tesla (T). A stronger field, a bigger current or a longer length of wire in the field gives a bigger force.

Checked against AQA GCSE Physics 8463 specification, 4.7.2.2 Fleming’s left-hand rule (HT)

15 / Magnetism and electromagnetismHigher only

Why does a coil carrying a current turn in a magnetic field?

  1. AThe current heats the coil and it expands
  2. BThe forces on its two sides act in the same direction
  3. CThe coil is pulled towards the nearest pole
  4. DThe forces on its two sides act in opposite directions
Show the answer

Answer: D The forces on its two sides act in opposite directions

In a motor, the current flows in opposite directions along the two sides of the coil, so the motor effect pushes one side up and the other down. This turns the coil. A bigger current or a stronger field makes it turn faster; reversing the current reverses it.

Checked against AQA GCSE Physics 8463 specification, 4.7.2.3 Electric motors (HT)

16 / Magnetism and electromagnetismHigher only · separate only

A magnet is pushed into a coil joined to a sensitive meter. What happens?

  1. ANothing, because there is no cell
  2. BThe magnet loses all its magnetism
  3. CA potential difference is induced and a current flows
  4. DThe coil becomes a permanent magnet
Show the answer

Answer: C A potential difference is induced and a current flows

When the magnetic field around a conductor changes, or the conductor moves through a field, a potential difference is induced across it. In a complete circuit this drives a current. No change means nothing is induced, and changing the field the other way reverses the current.

Checked against AQA GCSE Physics 8463 specification, 4.7.3.1 Induced potential (physics only, HT)

17 / Magnetism and electromagnetismHigher only · separate only

Which change gives a bigger induced potential difference?

  1. AMoving the magnet faster
  2. BUsing a coil with fewer turns
  3. CMoving the magnet more slowly
  4. DUsing a weaker magnet
Show the answer

Answer: A Moving the magnet faster

A faster change, a stronger magnet or more turns on the coil give a bigger induced potential difference. Reversing the motion or the field reverses it. The induced current’s own field always opposes the change that caused it.

Checked against AQA GCSE Physics 8463 specification, 4.7.3.1 Induced potential (physics only, HT)

18 / Magnetism and electromagnetismHigher only · separate only

What does an alternator generate?

  1. AA steady magnetic field
  2. BDirect current (d.c.)
  3. CAlternating current (a.c.)
  4. DStatic charge
Show the answer

Answer: C Alternating current (a.c.)

Generators use induction: a coil and a magnet turn relative to each other, so the field through the coil keeps changing and a potential difference is induced. An alternator gives a.c., which keeps reversing; a dynamo gives d.c., which stays in one direction.

Checked against AQA GCSE Physics 8463 specification, 4.7.3.2 Uses of the generator effect (physics only, HT)

19 / Magnetism and electromagnetismHigher only · separate only

Why does a transformer not work with a steady direct current?

  1. AA direct current is always too small
  2. BThe iron core blocks a direct current
  3. CA direct current cannot flow through coils
  4. DA steady current makes a field that does not change
Show the answer

Answer: D A steady current makes a field that does not change

An alternating current in the primary coil makes a changing magnetic field in the iron core, which is easily magnetised. The changing field passes through the secondary coil and induces an alternating potential difference. A steady d.c. gives an unchanging field, so nothing is induced.

Checked against AQA GCSE Physics 8463 specification, 4.7.3.4 Transformers (physics only, HT)

20 / Magnetism and electromagnetismHigher only · separate only

What does a step-up transformer have?

  1. AMore turns on the secondary coil than the primary
  2. BThe same number of turns on each coil
  3. CNo iron core between the coils
  4. DMore turns on the primary coil than the secondary
Show the answer

Answer: A More turns on the secondary coil than the primary

The ratio of the potential differences across the coils equals the ratio of their numbers of turns. A step-up transformer has more turns on the secondary, so its output potential difference is bigger; a step-down transformer has fewer, so its output is smaller.

Checked against AQA GCSE Physics 8463 specification, 4.7.3.4 Transformers (physics only, HT)

21 / Magnetism and electromagnetismHigher only · separate only

In a 100% efficient step-up transformer, how does the secondary current compare with the primary current?

  1. AIt is larger
  2. BIt is smaller
  3. CIt is zero
  4. DIt is the same
Show the answer

Answer: B It is smaller

If a transformer is 100% efficient, power in equals power out: Vp × Ip = Vs × Is. So when the potential difference is stepped up, the current is stepped down by the same factor. That is why the National Grid uses step-up transformers to cut the current in the cables.

Checked against AQA GCSE Physics 8463 specification, 4.7.3.4 Transformers (physics only, HT)

22 / Magnetism and electromagnetismHigher only · separate only

Which device turns the pressure changes in sound waves into a changing current?

  1. AA transformer
  2. BA loudspeaker
  3. CAn electric motor
  4. DA microphone
Show the answer

Answer: D A microphone

In a moving-coil microphone, sound waves push a diaphragm back and forth. A coil attached to it moves in a magnetic field, so a changing potential difference is induced. This makes a current that varies in the same pattern as the sound.

Checked against AQA GCSE Physics 8463 specification, 4.7.3.3 Microphones (physics only, HT)

23 / Magnetism and electromagnetismHigher only · separate only

Which device uses the motor effect to turn a changing current into sound?

  1. AA dynamo
  2. BA loudspeaker
  3. CA microphone
  4. DAn alternator
Show the answer

Answer: B A loudspeaker

A loudspeaker works the opposite way to a microphone. A changing current in a coil sitting in a magnetic field feels a changing force (the motor effect). The coil moves the cone back and forth, making pressure variations in the air: sound. Headphones work the same way.

Checked against AQA GCSE Physics 8463 specification, 4.7.2.4 Loudspeakers (physics only, HT)

02 / Longer answersMarked by levels

6-mark questions on this topic

Write your answer first, on paper. Then open it and tick off the points you made. How 6-mark questions are marked.

6 marks / How an electric motor worksHigher only

A simple d.c. motor has a rectangular coil of wire that can spin between the poles of a magnet. The coil is connected to a battery through a split-ring commutator, which reverses the direction of the current in the coil every half turn.

Explain how the motor works, and why reversing the current every half turn keeps the coil turning in the same direction.

What a full answer includes
  • When there is a current in the coil, the magnetic field of the current interacts with the field of the magnet.
  • A wire carrying a current across a magnetic field has a force on it: the motor effect.
  • The current flows in opposite directions along the two sides of the coil, so the forces on the two sides are in opposite directions, as Fleming’s left-hand rule shows.
  • One side is pushed up and the other down, so the coil turns.
  • After half a turn the forces would push the coil back the other way if nothing changed.
  • The split-ring commutator reverses the direction of the current in the coil every half turn.
  • This reverses the forces on the sides of the coil, so the coil keeps turning in the same direction.
  • The coil turns faster with a bigger current, a stronger magnetic field or more turns on the coil.

Model answer

When the battery drives a current through the coil, the magnetic field produced by the current interacts with the field of the permanent magnet. A wire carrying a current across a magnetic field has a force on it, which is called the motor effect. The current flows in opposite directions along the two sides of the coil, so by Fleming’s left-hand rule the forces on the two sides are in opposite directions: one side is pushed up and the other is pushed down. These two forces make the coil turn. If nothing changed, after half a turn the forces would push the coil back the other way, so it would just rock to and fro. The split-ring commutator stops this happening. It reverses the direction of the current in the coil every half turn, which reverses the forces on the two sides, so the coil keeps turning in the same direction. The motor can be made to turn faster by increasing the current, using a stronger magnet or putting more turns on the coil.

Where marks slip

Answers often say a current is “induced” in the coil. In a motor the battery supplies the current and the force comes from the motor effect. Also link the commutator to the forces: reversing the current reverses the forces, so the coil keeps turning the same way.

6 marks / How a transformer worksHigher only · separate only

A transformer has a primary coil and a secondary coil wound on the same iron core. The secondary coil has more turns than the primary coil.

Explain how this transformer works and why the potential difference across the secondary coil is greater than across the primary coil.

What a full answer includes
  • An alternating current flows in the primary coil.
  • This produces a magnetic field in the iron core that keeps changing in size and direction.
  • Iron is used because it is easily magnetised, so it carries the changing magnetic field to the secondary coil.
  • The changing magnetic field passes through the secondary coil and induces an alternating potential difference across it.
  • If the secondary coil is part of a complete circuit, the induced potential difference drives an alternating current in it.
  • The ratio of the potential differences across the coils equals the ratio of the numbers of turns on the coils.
  • The secondary coil has more turns, so the potential difference across it is greater: this is a step-up transformer.
  • A transformer does not work with direct current, because a steady current makes a magnetic field that does not change, so no potential difference is induced.

Model answer

An alternating current flows in the primary coil. Because the current keeps changing in size and direction, it produces a magnetic field in the iron core that also keeps changing. Iron is used for the core because it is easily magnetised, so it carries the changing magnetic field through to the secondary coil. The two coils are not connected to each other, but the changing magnetic field passes through the secondary coil and induces an alternating potential difference across it. If the secondary coil is connected into a complete circuit, this potential difference drives an alternating current. The ratio of the potential differences across the two coils is equal to the ratio of the numbers of turns on them. The secondary coil has more turns than the primary coil, so the potential difference across it is greater, which makes this a step-up transformer. A transformer will not work with direct current, because a steady current produces a magnetic field that does not change, and a magnetic field must be changing to induce a potential difference.

Where marks slip

Many answers say the current flows from one coil to the other through the core. The coils are not joined: the changing magnetic field in the iron core induces the potential difference in the secondary coil.

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