Question

(a) Two circular coils A and B are placed closed to each other. If the current in the coil A is changed will some current be induced in the coil B? Give reason?
(b) State the rule to determine the direction of a:
(i) Magnetic field produced around a straight conductor carrying current.
(ii) Force experienced by a current straight conductor placed in a magnetic field which is perpendicular to it.
(iii) Current induced in a coil due to its rotation in a magnetic field.

Answer 1

(a)Yes current will be induced. Before current is changed a constant flux is present. When current is changed the flux changes in the coil B. By Faraday's law current is induced to oppose the flux change.

(b)

(1)Keep your right thumb in the direction of current and roll your fingers. The direction in which they roll(clockwise or anticlockwise) gives you the answer

(2)$F=v\times B$.Using your right palm curl you fingers from v to B direction. The upright thumb gives you the direction.

(3)First find the flux direction in the coil. Keep your right opposite to that direction and rotate your fingers. This will give you the direction of current