State the purpose of ratchet in a screw gauge.

State the purpose of the Contact process.

How is a fuse put in an electric circuit ? State the purpose of using a fuse in a circuit.

In a cathode ray tube state : the purpose of the fluorescent screen.

The diagram represents fractional distillation for separation of mixtures. Answer the following: State the purpose of the fractionating column in the apparatus.

State one use of a screw gauge .

Assuming negligible zero error, Find the thickness of the wire,If In a screw gauge, 5 complete rotations of the screw cause if to move a linear distance of 0.25 cm . There are 100 circular scale divisions. The thickness of a wire measured by this screw gauge gives a reading of 4 main scale divisions and 30 circular scale divisions.

State the purpose of using the following in an electric circuit. Ammeter

State the purpose of using the following in an electric circuit. Rheostat

(a) Describe the different steps in one complete cycle of PCR. (b) State the purpose of such an amplified DNA sequence.

Name the principle on which screw gauge works.