Radiation energy corresponding to the temperature T of the sun is E. If its temperature is doubled, then its radiation energy will be:
1. 32 E
2. 16 E
3. 8 E
4. 4 E

A sphere maintained at a temperature of 600 K, has a cooling rate R in an external environment of 200 K temperature. If its temperature falls to 400 K, then its cooling rate will be:

1. $\frac{3}{16}R$

2. $\frac{16}{3}R$

3. $\frac{9}{27}R$

4. None 

Two conducting slabs of heat conductivity \(K_{1} ~  \text{and}   ~K_{2}\) are joined as shown in fig. If the temperature at the ends of the slabs are \(\theta_{1}\  and\  \theta_{2} \ (\theta_{1}   >   \theta_{2} ),  \)then the final temperature \( \left(\theta\right)_{m} \)of the junction will be:

Gravitational force is required for:
1. stirring of liquid
2. convection
3. conduction
4. radiation

A black body has a wavelength ${\lambda }_m$ corresponding to maximum energy at 2000 K. Its wavelength corresponding to maximum energy at 3000 K will be:

1. $\frac{3}{2}{\lambda }_m$

2. $\frac{2}{3}{\lambda }_m$

3. $\frac{16}{81}{\lambda }_m$

4. $\frac{81}{16}{\lambda }_m$

A cylindrical rod has temperatures ${\mathrm{T}}_1$ $\mathrm{and}$ ${\mathrm{T}}_2$ at its ends. The rate of flow of heat is $Q_1$ cal/sec. If all the linear dimensions are doubled while keeping the temperature constant, then the rate of flow of heat $Q_2$ will be:

1. $4Q_1$

2. $2Q_1$

3. $\frac{Q_1}{4}$

4. $\frac{Q_1}{2}$

Wien's displacement law expresses the relation between:
 

Which of the following is closest to an ideal black body?

For a black body at a temperature of 727ºC, its radiating power is 60 watts and the temperature of the surroundings is 227ºC. If the temperature of the black body is changed to 1227ºC then its radiating power will be:

1. 304 W

2. 320 W

3. 240 W

4. 120 W

Consider two rods of the same length and different specific heats \((S_1,S_2)\) conductivities \((K_1,K_2)\) and area of cross-sections \((A_1,A_2)\) and both having temperature \(T_1\) and \(T_2\) at their ends. If the rate of loss of heat due to conduction is equal, then:
1. \(K_1A_1=K_2A_2\)
2. \(\frac{K_1A_1}{S_1}=\frac{K_2A_2}{S_2}\)
3. \(K_2A_1=K_1A_2\)
4. \(\frac{K_2A_1}{S_2}=\frac{K_1A_2}{S_1}\)