Edexcel - London Examinations GCE, January 1999 - Paper 2 Question 3

3.

a)

i) Current is flowing into the paper.

 

ii) The field in region A is of uniform strength.

 

iii) At B the field is stronger.

 

iv) The pattern shows that a force acts from the strong field towards the weak field – it acts like a catapult, in fact the resultant field is known as the ‘catapult field’.

v) The force acts towards the left (from B to C). (6 marks)

 

 

The coil turns such that PS moves outward away from the N-pole (or coil turns anticlockwise looking from above).

The coil vibrates about the same position depending on the frequency of the a.c. supply. (9 marks)

 

c)

i) No it can only measure d.c.

ii) The spring creates an unwinding couple so that when no current flows the pointer goes back to the zero mark

iii) A scale

      and

        a pointer are needed (5 marks)