Question 1 :
Corresponding to a given temperature, there is a wavelength $ \lambda_{m}$, for which the intensity of heat radiations is<br>

Question 2 :
The water is used as a coolant in motor car engines because it has a very ...... specific latent heat of fusion.

Question 3 :
A heated body emits radiation which has maximum&#160;intensity near the frequency $v_{o}$ . The emissivity&#160;of the material is $0.5$. If the absolute temperature&#160;of the body is doubled. Then :

Question 4 :
A copper weight and iron weight of the same mass were dropped from the same height on the ground Which of the weights had the higher temperature after the impact ? (specific heat of Cu $=$ 0.1 Kcal/ kg$^{o}C$ ;specific heat of iron $=$ 0.11 Kcal/kg$^{o}C$)&#160;<br/>

Question 5 :
The ratio of amplitudes of radiation emitted by a cylindrical source at distances $2r$ and $18r$ from its axis will be<br/>

Question 7 :
When the temperature of body is equal to that of atmosphere, then

Question 11 :
Write 'true' or 'false' for each statement: On touching a lump of ice, we feel cold because some heat passes from our body to the ice. <br>

Question 12 :
According to principle of calorimetry, heat absorbed by cold bodies is equal to heat released by hot bodies.

Question 14 :
How much heat is needed to melt the block of ice?

Question 15 :
When 60 calories of heat are supplied to 15 g of water, the rise in temperature is

Question 16 :
Without green house effect, the average temperature of earth's surface would have been:

Question 17 :
The temperature of equal masses of three different liquids A, B and C are ${12^ \circ }C$, ${19^ \circ }C$ and ${28^ \circ }C$ respectively. The temperature when A and B are mixed is ${16^ \circ }C$ and when B and C are mixed it is ${23^ \circ }C$. What should be the temperature when A and C are mixed?

Question 18 :
A body having $1680 J$ of energy is supplied to $100 g$ of water. If the entire amount of energy is converted into heat the rise in temperature of water (sp. heat of water = $4200 JKg^{ -1 }\ ^0C ^{ -1 } $)

Question 20 :
The pendulum of a clock is made of brass. If the clock keeps correct time at $20^{\circ}C$ .Calculate how many seconds per day will it loose at&#160;&#160;&#160;$35^{\circ}C$ $(\alpha $ for brass =$2 \times$ <br> $10^{-5} $ <br> $^oC$)

Question 21 :
Two rods, one of Al and other of steel, having initial lengths $l_1$ and $l_2$ are connected together to form a single rod of length $l_1 + l_2$. The coefficient of linear expansion of aluminium and steel are $\alpha_A$ and $\alpha_S$ respectively. If the length of each rod increases by same amount when the temperature is raised by $t^0$C then find the relation $\displaystyle \frac{l_1}{l_1 + l_2}$.

Question 22 :
One mole of an ideal gas expands against a constant external pressure of 1 atm from a volume of $10d{ m }^{ 3 }$ to a volume of $30d{ m }^{ 3 }$. What would be the work done in joules?

Question 23 :
The net power that will be radiated out, $P_{S}$, from the sphere after steady state conditions are reached is:

Question 24 :
A black coloured solid sphere of radius $R$ and mass $M$ is inside a cavity with vacuum inside. The walls of the cavity are maintained at temperature $T_0$. The initial temperature of the sphere is $3T_0$. If the specific heat of the material of the sphere varies as $\alpha T^3$ per unit mass with the temperature $T$ of the sphere, where $\alpha$ is a constant, then the time taken for the sphere to cool down to temperature $2T_0$ will be<br>($\sigma$ is Stefan Boltzmann constant)

Question 25 :
A solid body X of heat capacity C is kept in an atmosphere whose temperature is $T_A=300$K. At time $t=0$ the temperature of X is $T_0=400$K. It cools according to Newton's law of cooling. At time $t_1$, its temperature is found to be $350$K.<br>At this time $(t_1)$, the body X is connected to a large body Y at atmospheric temperature $T_A$, through a conducting rod of length L, cross-sectional area A and thermal conductivity K. The heat capacity of Y is so large that any variation in its temperature may be neglected. The cross-sectional area A of the connecting rod is small compared to the surface area of X. Find the temperature of X at time $t=3t_1$.<br>