An external pressure P is applied on a cube at 0°C so that it is equally compressed from all sides.K is the bulk modulus of the material of the cube and α is its coefficient of linear expansion. Suppose we want to bring the cube to its original size by heating. The temperature should be raised by

• 3α/PK

• 3PKα

• P/3αK

• P/3αK

12.

A long metallic bar is carrying heat from one of its ends to the other end under steady-state. The variation of temperature θ along the length x of the bar from its hot end is best described by which of the following figure. 

• 
• 
• 
• 

One end of a thermally insulated rod is kept at a temperature T₁ and the other at T₂. The rod is composed of two sections of lengths

• (k₂

• (k₂

• (k₁

• (k₁

If C_p and Cv denote the specific heats of nitrogen per unit mass at constant pressure and constant volume respectively, then

• C_p – C_v = R/28

• C_p −C_v = R/14

• C_p −C_v = R

• C_p −C_v = R

Assuming the sun to be a spherical body of radius R at a temperature of T K, evaluate the total radiant power, incident on Earth, at a distance r from the Sun.

where r₀ is the radius of the Earth and σ is Stefan’s constant

Two rigid boxes containing different ideal gases are placed on a table. Box A contains one mole of nitrogen at temperature T₀, while Box B contains one mole of helium at temperature (7/3) T₀. The boxes are then put into thermal contact with each other and heat flows between them until the gases reach a common final temperature. (Ignore the heat capacity of boxes). Then, the final temperature of the gases, T_f, in terms of T₀ is

The figure shows a system of two concentric spheres of radii r₁ and r₂ and kept at temperatures T₁ and T₂ respectively. The radial rate of flow of heat in a substance between the two concentric sphere is proportional to

A heater coil is cut into two equal parts and only one part is now used in the heater. The heat generated will now be

• doubled

• four times

• one fourth

• one fourth

If the temperature of the sun were to increase from T to 2T and its radius from R to 2R, then the ratio of the radiant energy received on earth to what it was previously will be

• 4

• 16

• 32

• 32

A radiation of energy E falls normally on a perfectly reflecting surface. The momentum transferred to the surface is

• E/c

• 2E/c

• Ec
• Ec