Heat is flowing through a conductor of length \(l\) from \(x=0\) to \(x=l\). If its thermal resistance per unit length is uniform, which of the subsequent graphs is accurate?
1. | 2. | ||
3. | 4. |
The pressure applied from all directions on a cube is P. The volume elasticity of the cube is β and the coefficient of volume expansion is α. How much should its temperature be raised to maintain the original volume?
1.
2.
3.
4.
The plots of intensity versus wavelength for three black bodies at temperatures , and respectively are as shown. Their temperatures are such that:
1. | \(\mathrm{T}_1>\mathrm{T}_2>\mathrm{T}_3 \) | 2. | \(\mathrm{T}_1>\mathrm{T}_3>\mathrm{T}_2 \) |
3. | \(\mathrm{T}_2>\mathrm{T}_3>\mathrm{T}_1 \) | 4. | \(\mathrm{T}_3>\mathrm{T}_2>\mathrm{T}_1\) |
The temperature of the two outer surfaces of a composite slab, consisting of two materials having coefficients of thermal conductivity K and 2K and thickness x and 4x, respectively are and ( > ). The rate of heat transfer through the slab, in a steady state is , with f which equals to:
1. 1
2.
3.
4.
A wall is made up of two layers, A and B. The thickness of the two layers is the same, but the materials are different. The thermal conductivity of A is double that of B. If in thermal equilibrium, the temperature difference between the two ends is \(36^{\circ}\mathrm{C}\)hen the difference in temperature between the two surfaces of A will be:
1. \(6^{\circ}\mathrm{C}\)
2. \(12^{\circ}\mathrm{C}\)
3. \(18^{\circ}\mathrm{C}\)
4. \(24^{\circ}\mathrm{C}\)
Two rods (one semi-circular and the other straight) of the same material and of the same cross-sectional area are joined as shown in the figure. Points \(A\) and \(B\) are maintained at different temperatures. The ratio of the heat transferred through a cross-section of a semi-circular rod to the heat transferred through a
cross-section of a straight rod at any given point in time will be:
1. \(2:\pi\)
2. \(1:2\)
3. \(\pi:2\)
4. \(3:2\)
The temperature of a body falls from \(50^{\circ}\mathrm{C}\) to \(40^{\circ}\mathrm{C}\) in 10 minutes. If the temperature of the surroundings is \(20^{\circ}\mathrm{C}\)hen the temperature of the body after another 10 minutes will be:
1. \(36.6^{\circ}\mathrm{C}\)
2. \(33.3^{\circ}\mathrm{C}\)
3. \(35^{\circ}\mathrm{C}\)
4. \(30^{\circ}\mathrm{C}\)
Steam at \(100^{\circ}\mathrm{C}\) is injected into 20 g of \(10^{\circ}\mathrm{C}\) water. When water acquires a temperature of \(80^{\circ}\mathrm{C}\), the mass of water present will be: (Take specific heat of water =1 cal g-1 \(^\circ\)C-1 and latent heat of steam = 540 cal g-1)
1. | 24 g | 2. | 31.5g |
3. | 42.5 g | 4. | 22.5 g |
The value of the coefficient of volume expansion of glycerin is \(5\times10^{-4}\) K-1. The fractional change in the density of glycerin for a temperature increase of \(40^\circ \mathrm{C}\) will be:
1. | \(0.015\) | 2. | \(0.020\) |
3. | \(0.025\) | 4. | \(0.010\) |
Two identical bodies are made of a material whose heat capacity increases with temperature. One of these is at \(100^{\circ} \mathrm{C}\), while the other one is at \(0^{\circ} \mathrm{C}\). If the two bodies are brought into contact, then assuming no heat loss, the final common temperature will be:
1. | \(50^{\circ} \mathrm{C}\) |
2. | more than \(50^{\circ} \mathrm{C}\) |
3. | less than \(50^{\circ} \mathrm{C}\) but greater than \(0^{\circ} \mathrm{C}\) |
4. | \(0^{\circ} \mathrm{C}\) |