(a) Define specific resistance.

(b) What happens to the specific resistance of a conductor if its length is doubled?

(c) Name a substance whose specific resistance remains almost unchanged with the increase in its temperature.

A car of mass 120 kg is moving at a speed 18 km/h and it accelerates to attain a speed of 54 km/h in 5 seconds. Calculate:

(a) the work done by the engine.

(b) the power of the engine.

(a) Which characteristic of sound is affected due to the larger surface of a school bell?

(b) Calculate the distance covered by the Ultrasonic wave having a velocity of 1.5 kms^-1 in 14 s, when it is received after reflection by the receiver of the SONAR.

We are able to see the T.V. channels clearly when we set T.V. on auto-tuning.

(a) Which phenomenon led to the clear visibility of the channels, due to auto tuning?

(b) Define the above phenomenon mentioned by you.

(c) Give any one more example of this phenomenon.