manganate

Question 1

define electric potential at a point in space

Answer 1

work done per unit charge to bring a positive charge from infinity to the point

Question 2

explain how current gets to the output of a transformer

Answer 2

changing flux on primary coil due to AC; iron core links flux to secondary coil; e.m.f. induced equal to rate of change of flux linkage

Question 3

a battery + switch in series are hooked up to a transformer; the transformer has output only for a short period of time when the switch is closed; explain this observation

Answer 3

flux change when switch is closed => e.m.f. induced; flux becomes constant due to constant current => no e.m.f.

Question 4

state faraday’s law

Answer 4

induced e.m.f. is equal to rate of change of flux linkage

Question 5

the north pole of a magnet is moved towards a coil, inducing a current in the coil; using conservation of energy, explain the polarity of the coil towards the magnet

Answer 5

also north; work done against repulsive force is converted to electrical energy in the coil

Question 6

what is magnetic flux

Answer 6

magnetic flux density x area normal to the field

Question 7

what is e.m.f.

Answer 7

energy transferred to electrical per unit charge

Question 8

why does speed not change during circular motion (despite there being a force)

Answer 8

force is perpendicular to velocity; so overall no work is done

Question 9

how to find directions of vectors when magnetic force is involved

Answer 9

fleming’s left hand rule