Q. No.A rod \(\mathrm{A}\) has a coefficient of thermal expansion \((\alpha_A)\) which is twice of that of rod \(\mathrm{B}\) \((\alpha_B)\). The two rods have length \(l_A,~l_B\) where \(l_A=2l_B\). If the two rods were joined end-to-end, the average coefficient of thermal expansion is:
1.
\(\alpha_A\)
2.
\(\dfrac{2\alpha_A}{6}\)
3.
\(\dfrac{4\alpha_A}{6}\)
4.
\(\dfrac{5\alpha_A}{6}\)
The ice-point reading on a thermometer scale is found to be \(20^\circ,\) while the steam point is found to be \(70^\circ.\) When this thermometer reads \(100^\circ ,\) the actual temperature is:
1. \(80^\circ\text{C}\)
2. \(130^\circ\text{C}\)
3. \(160^\circ\text{C}\)
4. \(200^\circ\text{C}\)
The temperature at which the Celsius and Fahrenheit thermometers agree (to give the same numerical value) is:
| 1. | \(-40^\circ\) | 2. | \(40^\circ\) |
| 3. | \(0^\circ\) | 4. | \(50^\circ\) |
Two rods of identical dimensions are joined end-to-end, and the ends of the composite rod are kept at \(0^\circ\text{C}\) and \(100^\circ\text{C}\) (as shown in the diagram). The temperature of the joint is found to be \(40^\circ\text{C}.\) Assuming no loss of heat through the sides of the rods, the ratio of the conductivities of the rods \(\dfrac{K_1}{K_2}\) is:
| 1. | \(\dfrac32\) | 2. | \(\dfrac23\) |
| 3. | \(\dfrac11\) | 4. | \(\dfrac{\sqrt3}{\sqrt2}\) |
(\(\theta_1\)\(^\circ \text{C}\)) and the right end (\(\theta_2\)\(^\circ \text{C}\)) are:
| 1. | \(\theta_{1}=0, ~\theta_{2}=90\) |
| 2. | \(\theta_{1}=10,~\theta_{2}=85\) |
| 3. | \(\theta_{1}=20, ~\theta_{2}=80\) |
| 4. | \(\theta_{1}=30, ~\theta_{2}=100\) |
1. \(45\) W
2. \(50\) W
3. \(60\) W
4. \(80\) W
The first liquid has a mass flow rate \(\left(\dfrac{dm}{dt}\right)=r_1,\) and its temperature rises by \(\Delta\theta_1.\) For the second liquid, the flow rate \(\left(\dfrac{dm}{dt}\right)=r_2,\) and the temperature fall is \(\Delta\theta_2.\) The ratio of their specific heat capacities is:
| 1. | \(\dfrac{\Delta\theta_1}{\Delta\theta_2}\) | 2. | \(\dfrac{r_1}{r_2}\) |
| 3. | \(\dfrac{r_2\Delta\theta_2}{r_1\Delta\theta_1}\) | 4. | \(\dfrac{r_2\Delta\theta_1}{r_1\Delta\theta_2}\) |
1. \(12\) minutes
2. \(9\) minutes
3. \(8\) minutes
4. \(7\) minutes
A solid at temperature \(T_1\), is kept in an evacuated chamber at temperature \(T_2>T_1\). The rate of increase of temperature of the body is proportional to:
1. \(T_2-T_1\)
2. \(T^2_2 -T^2_1 \)
3. \(T^3_2 -T^3_1\)
4. \(T^4_2 -T^4_1\)
In a room containing air, heat can go from one place to another:
1. by conduction only
2. by convection only
3. by radiation only
4. by all three modes
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