P4.2

Question 1

Explain how a commutator keeps the coil spinning

Answer 1

Every half turn, each ring is connected to a different end of the power supply. The direction of the current changes and as a result the direction of the force changes. This ensures that the coil rotates in the same direction.

Question 2

what is magnetic flux density measured in?

Answer 2

Tesla

Question 3

equation for force

Answer 3

force = magnetic flux density x current x length

Question 4

what happens to the current during the coils turn?

Answer 4

current changes direction every half turn

Question 5

what happens to the forces on the coil during the turn?

Answer 5

forces on either side change direction every half turn

Question 6

commutator

Answer 6

copper ring spilt into two parts

Question 7

why at one point in the turn is there no forces acting on the coil?

Answer 7

the circuit is broken

Question 8

why does the coil not stop when the circuit is broken?

Answer 8

because of the momentum

Question 9

what happens when you put a wire carrying a current in another magnetic field?

Answer 9

the two fields add together

Question 10

what is the motor effect?

Answer 10

a force will move the wire away from the strong part of the field and go towards the weak part of the field, this movement is called the motor effect

Question 11

what is flemmings left hand rule?

Answer 11

F-force
B-magnetic field
I-current