p4.2

Question 1

electric motor (how does it work )

Answer 1

one side of the coil pushes upwards (other downwards) (can be checked using FBIL)
when rotates 90 degrees (vertical line) there is no force and current
at this point the split ring commutator reverses the current direction which continues the rotation of the motor in the right direction

Question 2

what is Electromagnetic induction

Answer 2

producing an induced potential difference across the ends of a wire.
moving a conductor in a magnetic field or changing the magnetic field around à conductor

Question 3

how is p.d induced on a wire changed

Answer 3

length of wire (in field)
rate at which field lines are cut

Question 4

how to increase induced p.d

Answer 4

moving wire faster
using a stronger magnetic field
using more wire

Question 5

how do you know the direction of an induced p.d

Answer 5

when a current flows in a conductor it produces a magnetic field
so the magnetic field produced is in the opposite direction to the field that produces the p.d

Question 6

how does a dynamo work and why à direct current is induced in the coil

Answer 6

-coil moves through magnetic field
-pd induced across
-complete circuit therefore à current is induced
-every half turn the two end of the coil swap from one brush to the other
-so the direction of current does not reverse every half rotation

Question 7

how a magnet and a current carrying conductor exert a force on one another

Answer 7

À wire carrying à current creates a magnetic field. this magnetic field interacts with another magnetic field causing a force pushing the wire at right angles (motor effect)

Question 8

Alternator

Answer 8

converts mechanical energy into electrical energy and P.d is induced across the ends of à wire