The motor effect

Question 1

A current carrying wire……

Answer 1

A current carrying wire in the presence of a magnetic field will experience a force.

Question 2

What happens when a current carrying wire a place inbetween N and S pole of 2 magnets.

Answer 2

-The magnetic fields interact
-There is a force acting on the wire

Question 3

What is required for the wire to experience full force?

Answer 3

-The wire has to be perpendicular to the magnetic field.

Question 4

How do you find the direction of the force?

Answer 4

-Find the direction of the current
-Find the direction of the magnetic field

-Use Flemmings LHR

Question 5

Which fingers symbolise current, magnetic field and force in Flemming’s LHR?

Answer 5

-1st Finger is direction of magnetic field (N to S)
-2nd finger is the direction of the current
-The thumb is the direction of the force

Question 6

Describe the set-up with a horseshoe magnet and current carrying rails (wires)

Answer 6

-The rails on the horseshoe magnet are fixed, with one on top that is free to roll.

-A current can flow within these rails
-When there’s a power source, rails generate a mag field, this interacts with mag field of horseshoe magnet.

-Rails experience a force

Question 7

What is the role of a commutator in a d.c. motor

Answer 7

-The current in the coil is reversed every half turn
-To ensure the force is always in the same direction as the motor is d.c.