- 1(current)
Q. No.In a Carnot engine, when \(T_2=0^\circ \mathrm{C}\) and \(T_1=200^\circ \mathrm{C},\) its efficiency is \(\eta_1\) and when \(T_1=0^\circ \mathrm{C}\) and \(T_2=-200^\circ \mathrm{C},\) its efficiency is \(\eta_2.\) What is the value of \(\frac{\eta_1}{\eta_2}?\)
| 1. | 0.577 | 2. | 0.733 |
| 3. | 0.638 | 4. | cannot be calculated |
1. \(\frac{\eta}{2}\)
2. \(\eta\)
3. \(2\eta\)
4. \(3\eta\)
Two Carnot engines A and B are operated in succession. The first one, A receives heat from a source at \(T_1=800\) K and rejects to sink at \(T_2\) K. The second engine, B, receives heat rejected by the first engine and rejects to another sink at \(T_3=300\) K. If the work outputs of the two engines are equal, then the value of \(T_2\) will be:
| 1. | 100 K | 2. | 300 K |
| 3. | 550 K | 4. | 700 K |
A reversible engine converts one-sixth of the heat input into work. When the temperature of the sink is reduced by \(62^{\circ}\mathrm{C}\), the efficiency of the engine is doubled. The temperatures of the source and sink are:
1. \(80^{\circ}\mathrm{C}, 37^{\circ}\mathrm{C}\)
2. \(95^{\circ}\mathrm{C}, 28^{\circ}\mathrm{C}\)
3. \(90^{\circ}\mathrm{C}, 37^{\circ}\mathrm{C}\)
4. \(99^{\circ}\mathrm{C}, 37^{\circ}\mathrm{C}\)
If the temperature of the source and the sink in the heat engine is at 1000 K & 500 K respectively, then the efficiency can be:
1. 20%
2. 30%
3. 50%
4. All of these
Two Carnot engines x and y are working between the same source temperature \(T_1\) and the same sink temperature \(T_2\). If the temperature of the source in Carnot engine x is increased by \(\Delta T\), and in the Carnot engine y, the temperature of the sink is increased by\(\Delta T\), then the efficiency of x and y becomes \(\eta_\mathrm x\) and\(\eta_\mathrm y\). Then:
| 1. | \(\eta_{\mathrm{x}}=\eta_{\mathrm{y}}\) |
| 2. | \(\eta_{\mathrm{x}}<\eta_{\mathrm{y}}\) |
| 3. | \(\eta_{\mathrm{x}}>\eta_{\mathrm{y}}\) |
| 4. | The relation between \(\eta_{\mathrm{x}}\) and \(\eta_{\mathrm{y}}\) depends on the nature of the working substance |
The efficiency of a Carnot heat engine working between the temperatures \(27^{\circ}\mathrm{C}\) and \(227^{\circ}\mathrm{C}\) is:
1. 0.1
2. 0.6
3. 0.2
4. 0.4
When the sink temperature is kept at \(400~\text{K},\) the efficiency of a Carnot engine is \(50\text{%}.\) While keeping the source temperature constant, by how much should we reduce the sink temperature to increase the efficiency to \(60\text{%}\text{?}\)
| 1. | \(80\) K | 2. | \(70\) K |
| 3. | \(320\) K | 4. | \(240\) K |
The efficiency of a Carnot engine is \(40\%\) when it receives energy at \(500 ~\text K.\) At what temperature it should receive energy to increase its efficiency by \(25\%?\)
| 1. | \(600 ~\text K\) | 2. | \(700 ~\text K\) |
| 3. | \(800 ~\text K\) | 4. | \(900 ~\text K\) |
| 1. | \(275~\text{K}\) | 2. | \(325~\text{K}\) |
| 3. | \(250~\text{K}\) | 4. | \(380~\text{K}\) |
- 1(current)
Q. No.
© 2026 GoodEd Technologies Pvt. Ltd.