Wien's displacement law expresses the relation between:
 

1.	Wavelength corresponding to maximum energy and temperature
2.	Radiation energy and wavelength
3.	Temperature and wavelength
4.	Colour of light and temperature

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. \(\frac{K_2A_1}{S_2}=\frac{K_1A_2}{S_1}\)

Unit of Stefan's constant is:

1. Watt-m²-K⁴

2. Watt-m²/K⁴

3. Watt/m²–K

4. Watt/m² K⁴

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. $\frac{Q_1}{2}$

We consider the radiation emitted by the human body. Which of the following statements is true:
 

Consider a compound slab consisting of two different materials having equal thicknesses and thermal conductivities K and 2K, respectively. The equivalent thermal conductivity of the slab will be:

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