Motoring Flashcards
1
Q
The right hand grip rule
A
2
Q
What is the field pattern like?
A
The field pattern due to a long coil of wire is similar to that of a bar magnet.
3
Q
What happens when a wire is placed between the poles of a magnet?
A
The wire moves out of the gap when the current is switched on.
4
Q
If the direction of the current is reversed
A
The wire moves in the opposite direction.
5
Q
How can the polarity be predicted with the current direction?
A
- North pole: Anticlockwise
- South pole: Clockwise
6
Q
Fleming’s left hand rule
A
7
Q
What is the direction of the field, current and motion.
A
They are all at right angles to eachother.
8
Q
Turning Coils
A
- When a current passes through a coil, placed between the poles of a magnet, there is a force on each side of the coil.
- Using Fleming’s left hand rule, you can see that the forces on each side of the coil are in opposite directions, the other is forced down.
- The coil starts to spin.
9
Q
The motor spins faster when:
A
- The number of turns on the coil is increased.
- The size of the current is increased.
- The strength of the magnetic field is increased.
10
Q
Job of the commutator
A
The job of the commutator is to make the motor continue to spin.
11
Q
What happens to current in coil?
A
- The direction of the current in the coil is reversed every half turm.
- This makes sure the force on the coil is always in the same direction.
12
Q
Magnets in practical motors
A
- The magnets in practical motors have curved poles to give a radial magnetic field.
- A radial field increases the force on the coil and keeps it constant as the motor turns.
