Give the principle of photocell.

Give the principle of superposition.

Give the principle of a transformer, construction of a stepdown transformer. Give any two energy losses of a transformer.

State the principle of optical pipe.

State the principle of a potentiometer.

Define the principle of hydrogen bomb.

Give the principle, construction and working of an a.c. generator.

Give the principle, construction and labelled diagram of AC generator.

Give the principle and two applications of optical fibres.