GCSE Combined Science Magnetism & motors questions by topic

A student investigates two bar magnets and some metal rods on a balance tray.

1. (a)State what happens when the two north poles of the magnets are brought close together.[1]
2. (b)Circle the two magnetic materials from this list: copper, steel, aluminium, cobalt.[1]
3. (c)Explain what is meant by an induced magnet.[2]

This question is about making a strong electromagnet.

1. (a)Describe how a solenoid’s magnetic field compares with a bar magnet’s.[1]
2. (b)State two ways to increase the strength of an electromagnet.[2]
3. (c)Name one device that uses an electromagnet.[1]

A wire carrying a current is clamped between the poles of a magnet.

1. (a)Name the effect that produces a force on the wire.[1]
2. (b)State what happens to the force if the current is made larger.[1]
3. (c)State one way to reverse the direction of the force.[1]
4. (d)The wire is turned so it lies parallel to the field. State the size of the force now.[1]

This question is about plotting a magnetic field.

1. (a)Name the instrument used to find the direction of a magnetic field at a point.[1]
2. (b)Describe how the instrument is used to plot the field of a bar magnet.[2]
3. (c)State the direction of the field lines outside the magnet.[1]

A teacher demonstrates the motor effect with a foil-covered rod carrying a current between magnet poles.

1. (a)Explain why the rod moves when the current is switched on.[2]
2. (b)State three ways to increase the size of the force on the rod.[3]

This question is about calculating motor-effect forces (Higher).

1. (a)Write the equation linking force, flux density, current and length.[1]
2. (b)Calculate the force on a wire carrying 2.5 A perpendicular to a 0.40 T field, with 0.080 m of wire in the field.[3]
3. (c)The current is increased to 6.0 A. Calculate the new force.[1]

A hospital wants a switchable magnet for a security door system.

1. (a)Explain why an electromagnet suits this job better than a permanent magnet.[2]
2. (b)Describe how the electromagnet is constructed.[2]
3. (c)State what happens to the poles if the current is reversed.[1]

This question is about predicting motor-effect directions (Higher).

1. (a)Name the rule used to predict the direction of the force.[1]
2. (b)State what each part of the hand represents.[3]
3. (c)A student uses their right hand for the rule. Explain why the answer will be wrong.[1]

A 0.36 N force acts on a 0.30 m length of wire carrying 4.0 A, perpendicular to an unknown field (Higher).

1. (a)Calculate the magnetic flux density, including the unit.[3]
2. (b)The wire is rotated until it lies parallel to the field. State and explain the new force.[2]

This question is about the DC motor (Higher).

1. (a)Explain why the coil of a DC motor begins to rotate when the current is switched on.[2]
2. (b)Explain the role of the split-ring commutator and brushes.[3]
3. (c)State two changes that make the motor spin faster.[1]

Two students argue about changing a motor-effect setup. The wire carries 3.0 A in a 0.10 T field with 0.20 m in the field (Higher).

1. (a)Calculate the starting force.[2]
2. (b)Student A reverses the current and Student B then also flips the magnet. Calculate the new force and state its direction compared with the original.[2]
3. (c)Student C suggests tripling the current instead. Calculate the force with 9.0 A.[1]

Compare permanent magnets and electromagnets for two jobs.

1. (a)A fridge door catch must hold constantly with no power supply. Recommend a magnet type and explain why.[2]
2. (b)An automated line must drop steel parts into a bin on demand. Recommend a magnet type and explain why.[2]
3. (c)State two ways the strength of your chosen magnet in part (b) can be adjusted.[2]