Practise demonstrating the motor effect and determining force directions for current-carrying conductors, coils and charged-particle beams in magnetic fields.
A wire AB hangs loosely between the N pole and the S pole of a strong magnet.
Fig. 10.1 shows the arrangement.
Fig. 10.1
The wire is connected to a power supply.
When the power supply is switched on, there is a very large direct current (d.c.) in the wire in the direction from B to A.
Describe what happens to the wire as the power supply is switched on.
The power supply is adjusted and there is now a large alternating current (a.c.) in the wire.
Describe what happens to the wire.
Fig. 9.1 shows a simple direct current (d.c.) electric motor. The coil rotates about the axis when there is a current in the coil. The coil is connected to the rest of the circuit by the brushes.
Fig. 9.1
On Fig. 9.1, draw a pair of arrows to show which way the coil rotates. Explain the direction you have chosen.
An electron source produces a narrow beam of electrons that all travel at the same speed.
The electron source is placed in a vacuum and the beam of electrons travels vertically downwards. Fig. 7.1 shows the beam of electrons before it passes between the N -pole and the S-pole of a magnet.
Fig. 7.1
Describe and explain what happens to the beam of electrons in the magnetic field between the poles of the magnet in Fig. 7.1.