1.1. Higher Tier Only

Figure 1 shows equipment which demonstrates the motor effect.

Figure 1

A piece of copper wire (Q) is placed on two bare wires connected to a cell and switch.

Describe what happens to wire Q when the switch is closed.

1.2. Higher Tier Only

Describe any differences in the motion of Q for the following changes:

(i) The direction of the magnetic field is reversed.

[1]

 (ii) The cell is replaced with a cell of higher voltage. 

[1]

1.3. Higher Tier Only

Figure 2 shows two identical metal bars freely suspended inside a coil of insulated wire.

Figure 2

A direct current passes through the coil, then the metal bars move apart.

Explain why the metal bars move apart.

1.4. Higher Tier Only

The d.c. supply is removed and the metal rods return to their starting places.

Suggest a material that the metal rods could be made from. Explain why you chose this.