A copper wire of radius r and length l has a resistance of R. A second copper wire with radius 2r and length l is taken and the two wires are joined in a parallel combination. The resultant resistance of the parallel combination of the two wires will be

Which of the following terms is not used in the field of physics?

A. Latent heat

B. Nuclear fusion

C. Refractive index

D. Stock value

Radiocarbon is produced in the atmosphere as a result of

A. Collision between fast neutrons and nitrogen nuclei present in the atmosphere.

B. Action of ultraviolet light from the sun on atmospheric oxygen.

C. Action of solar radiations particularly cosmic rays on carbon dioxide present in the atmosphere.

D. Lightning discharge in atmosphere.

It is easier to roll a stone up a sloping road than to lift it vertical upwards because

A. Work done in rolling is more than in lifting.

B. Work done in lifting the stone is equal to rolling it.

C. Work done in both is same but the rate of doing work is less in rolling.

D. Work done in rolling a stone is less than in lifting it.

The absorption of ink by blotting paper involves:

A. Viscosity of ink

B. Capillary action phenomenon

C. Diffusion of ink through the blotting

D. Siphon action