Electromagnetism

This question is about magnets and magnetism.

Figure 8 shows a magnet that has picked up three paper clips.

The poles of the lowest paper clip are labelled.

Label the poles of the other two paper clips in Figure 8.

Complete the sentence, by choosing a word from the box, to describe the type of magnetism that these paper clips have.

These paper clips have_........ magnetism.

Suggest a material that these paper clips in Figure 8 could be made from.

When the paper clips were pulled off the magnet they fell separately to the table.

Describe how you could test whether any of the paper clips had kept any magnetism.

Figure 9 shows the magnetic field around a wire carrying a current.

State how you can tell from Figure 9 that the strength of the field is greater at P than at Q.

The magnetic field strength is measured at P for different values of current in the wire.

The results of this investigation are shown in Figure 10.

Describe the relationship between magnetic field strength and current.

Figure 6 shows some objects and words describing these objects.

Draw one line from each object to its description.

object description

Figure 7 shows a wire passing through a piece of card. The wire carries an electric current.

Figure 7

Draw one magnetic field line on Figure 7, to show the shape of the magnetic field produced by the current.

Draw one arrow on the field line you have drawn to show the direction of the magnetic field.

A student measures the strength of the magnetic field at several distances from the wire in Figure 7. Figure 8 shows most of the student’s results.

Figure 9 shows two extra sets of results. mT is a unit of strength of a magnetic field.

Plot the two extra points on Figure 8.

Draw a best fit curve on the graph in Figure 8.

Use the graph in Figure 8 to calculate the change in strength of magnetic field when the distance from the wire changes from 4 cm to 8 cm.

change in strength of magnetic field =_........

The distance from the wire affects the strength of the magnetic field.

State one other factor that affects the strength of the magnetic field.

Figure 11 shows the magnetic field of a magnet.

At which point is the magnetic field strongest?

Figure 12 shows a wire carrying a current.

Draw, on the card in Figure 12, the magnetic field that is produced by the current.

Figure 13 shows two metal rods carrying a current.

A metal roller touches both rods and completes the circuit. The roller is in the magnetic field produced by a magnet.

The magnetic flux density of the magnetic field at the roller is 1.2 T.

The current in the roller is 2.5 A.

The length of the roller carrying the current is 0.060 m.

Calculate the force on the roller.

Use the equation

Describe how Fleming’s left‑hand rule can be used to determine the direction of the force acting on the roller.

You may draw a diagram to help your answer.

Draw an arrow on Figure 13 to show the direction of the force acting on the roller.

Which of these is a magnetic material?

A student has

− a power pack

− a long piece of wire

− a stiff card

− iron filings

Describe how the student could use this equipment to show the shape of the magnetic field produced by a current in the wire.

You may draw a diagram to help with your answer.

Figure 5 shows two magnetic poles facing each other.

The magnetic field between the poles is uniform.

On Figure 5, draw the magnetic field lines between the two poles and show the direction of this magnetic field.

Figure 5

A student uses a plotting compass to investigate the magnetic field around a wire.

Figure 10 shows the wire going straight through a card.

Figure 10 shows the compass needle when there is no current in the wire.

Which of these shows a possible direction of the compass needle when there is a current in the wire going from P to Q?

Describe how the student could develop the investigation to find the shape of the magnetic field produced by the current.

Figure 11 shows a copper wire between two magnetic poles.

The current in the wire is in the direction shown by the arrow.

The wire experiences a force due to the magnetic field.

The direction of the force due to the magnetic field is

The interaction between the magnetic fields produced by the magnet and the current in the wire produces forces on the magnet and the wire.

Compare these two forces.

Figure 12 shows a different wire inside a uniform magnetic field.

The magnetic flux density of the magnetic field is 0.72 N/A m. The length of the wire inside the field is 30 mm. The size of the force due to the magnetic field on the wire is 0.045 N.

Calculate the size of the current in the wire.

Use an equation selected from the list of equations at the end of this paper.

A student has a bar magnet, a piece of iron the same size as the magnet, and some paper clips.

Describe how the student could use these items to demonstrate temporary induced magnetism.

A student sets up the apparatus shown in Figure 9.

When the current in the solenoid is switched on, the solenoid attracts the iron nail.

Describe how the student could use this apparatus to investigate how the size of the current in the solenoid affects the force of attraction between the solenoid and the iron nail.

The spring constant of a different spring is 24 N/m.

The spring is extended from its unstretched length by 12 cm.

Calculate the energy transferred in extending the spring by 12 cm.

Use an equation selected from the list of equations at the end of this paper.