371302
If the temperature of a source increases, the efficiency of a heat engine
1 Increases
2 Decreases
3 Remains unchanged
4 None of these
Explanation:
Conceptual Question
PHXI12:THERMODYNAMICS
371303
An ideal heat engine working between temperatures \(T_{H}\) abd \(T_{L}\) has efficiency \(\eta\). If both the temperature are raised by \(100\;K\) each, the new efficiency of the heat engine will be:
1 Equal to \(\eta\)
2 Greater than \(\eta\)
3 Less than \(\eta\)
4 Greater or less than \(\eta\) depending upon the nature of the working substance
371304
If heat \(Q\) is added reversibly to a system at temperature \(T\) and heat \(Q^{\prime}\) is taken away from it reversibly at temperature \(T^{\prime}\), then which one of the following is correct
3 \(\dfrac{Q}{T}-\dfrac{Q^{\prime}}{T^{\prime}}=\) change in internal energy of the system
4 \(\dfrac{Q}{T}-\dfrac{Q^{\prime}}{T} < 0\)
Explanation:
In a reversible cycle \(\dfrac{Q}{T}=\dfrac{Q^{\prime}}{T^{\prime}}\)
PHXI12:THERMODYNAMICS
371305
A motor cycle engine delivers a power \(10\;kW\), by consuming petrol at the rate of \(2.4\;kg/hour\). If the calorific value of petrol is \(35.5\,MJ/kg\), the rate of heat rejection by the exhaust is
1 \(13.7\;kW\)
2 \(5.5\;kW\)
3 \(9.7\;kW\)
4 \(11.2\;kW\)
Explanation:
Heat received (or produced by the burning of petrol) in hour will be \( = (2.4\;kg/{\rm{ }}hour{\rm{ }})(35.5\,MJ/kg)\) \( = 85.2 \times {10^6}\;J/hour\) \(\therefore\) The rate at which heat is received \( = \frac{{85.2 \times {{10}^6}\;J}}{{(3600\;s)}} = 2.37 \times {10^4}\;J/s = 23.7\;k\,W\) The rate of heat rejection \(=\) rate at which heat is produced-rate at which work is done \( = 23.7\;k\,W - 10\;k\,W = 13.7\;k\,W\)
PHXI12:THERMODYNAMICS
371306
Assertion : A reversible engine working between \(127^{\circ} \mathrm{C}\) and \(227^{\circ} \mathrm{C}\) cannot have efficiency more than \(20 \%\). Reason : Under ideal conditions \(\eta=1-\left(T_{2} / T_{1}\right)\).
1 Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
\({T_1} = 227 + 273 = 500\;K\) \({T_2} = 127 + 273 = 400\;K\) \(\eta_{\text {max }}=1-\dfrac{T_{2}}{T_{1}}=1-\dfrac{400}{500}=0.2\) \(\eta_{\max }=20 \%\) (As this is maximum, Assertion is true). So correct option is (1).
371302
If the temperature of a source increases, the efficiency of a heat engine
1 Increases
2 Decreases
3 Remains unchanged
4 None of these
Explanation:
Conceptual Question
PHXI12:THERMODYNAMICS
371303
An ideal heat engine working between temperatures \(T_{H}\) abd \(T_{L}\) has efficiency \(\eta\). If both the temperature are raised by \(100\;K\) each, the new efficiency of the heat engine will be:
1 Equal to \(\eta\)
2 Greater than \(\eta\)
3 Less than \(\eta\)
4 Greater or less than \(\eta\) depending upon the nature of the working substance
371304
If heat \(Q\) is added reversibly to a system at temperature \(T\) and heat \(Q^{\prime}\) is taken away from it reversibly at temperature \(T^{\prime}\), then which one of the following is correct
3 \(\dfrac{Q}{T}-\dfrac{Q^{\prime}}{T^{\prime}}=\) change in internal energy of the system
4 \(\dfrac{Q}{T}-\dfrac{Q^{\prime}}{T} < 0\)
Explanation:
In a reversible cycle \(\dfrac{Q}{T}=\dfrac{Q^{\prime}}{T^{\prime}}\)
PHXI12:THERMODYNAMICS
371305
A motor cycle engine delivers a power \(10\;kW\), by consuming petrol at the rate of \(2.4\;kg/hour\). If the calorific value of petrol is \(35.5\,MJ/kg\), the rate of heat rejection by the exhaust is
1 \(13.7\;kW\)
2 \(5.5\;kW\)
3 \(9.7\;kW\)
4 \(11.2\;kW\)
Explanation:
Heat received (or produced by the burning of petrol) in hour will be \( = (2.4\;kg/{\rm{ }}hour{\rm{ }})(35.5\,MJ/kg)\) \( = 85.2 \times {10^6}\;J/hour\) \(\therefore\) The rate at which heat is received \( = \frac{{85.2 \times {{10}^6}\;J}}{{(3600\;s)}} = 2.37 \times {10^4}\;J/s = 23.7\;k\,W\) The rate of heat rejection \(=\) rate at which heat is produced-rate at which work is done \( = 23.7\;k\,W - 10\;k\,W = 13.7\;k\,W\)
PHXI12:THERMODYNAMICS
371306
Assertion : A reversible engine working between \(127^{\circ} \mathrm{C}\) and \(227^{\circ} \mathrm{C}\) cannot have efficiency more than \(20 \%\). Reason : Under ideal conditions \(\eta=1-\left(T_{2} / T_{1}\right)\).
1 Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
\({T_1} = 227 + 273 = 500\;K\) \({T_2} = 127 + 273 = 400\;K\) \(\eta_{\text {max }}=1-\dfrac{T_{2}}{T_{1}}=1-\dfrac{400}{500}=0.2\) \(\eta_{\max }=20 \%\) (As this is maximum, Assertion is true). So correct option is (1).
371302
If the temperature of a source increases, the efficiency of a heat engine
1 Increases
2 Decreases
3 Remains unchanged
4 None of these
Explanation:
Conceptual Question
PHXI12:THERMODYNAMICS
371303
An ideal heat engine working between temperatures \(T_{H}\) abd \(T_{L}\) has efficiency \(\eta\). If both the temperature are raised by \(100\;K\) each, the new efficiency of the heat engine will be:
1 Equal to \(\eta\)
2 Greater than \(\eta\)
3 Less than \(\eta\)
4 Greater or less than \(\eta\) depending upon the nature of the working substance
371304
If heat \(Q\) is added reversibly to a system at temperature \(T\) and heat \(Q^{\prime}\) is taken away from it reversibly at temperature \(T^{\prime}\), then which one of the following is correct
3 \(\dfrac{Q}{T}-\dfrac{Q^{\prime}}{T^{\prime}}=\) change in internal energy of the system
4 \(\dfrac{Q}{T}-\dfrac{Q^{\prime}}{T} < 0\)
Explanation:
In a reversible cycle \(\dfrac{Q}{T}=\dfrac{Q^{\prime}}{T^{\prime}}\)
PHXI12:THERMODYNAMICS
371305
A motor cycle engine delivers a power \(10\;kW\), by consuming petrol at the rate of \(2.4\;kg/hour\). If the calorific value of petrol is \(35.5\,MJ/kg\), the rate of heat rejection by the exhaust is
1 \(13.7\;kW\)
2 \(5.5\;kW\)
3 \(9.7\;kW\)
4 \(11.2\;kW\)
Explanation:
Heat received (or produced by the burning of petrol) in hour will be \( = (2.4\;kg/{\rm{ }}hour{\rm{ }})(35.5\,MJ/kg)\) \( = 85.2 \times {10^6}\;J/hour\) \(\therefore\) The rate at which heat is received \( = \frac{{85.2 \times {{10}^6}\;J}}{{(3600\;s)}} = 2.37 \times {10^4}\;J/s = 23.7\;k\,W\) The rate of heat rejection \(=\) rate at which heat is produced-rate at which work is done \( = 23.7\;k\,W - 10\;k\,W = 13.7\;k\,W\)
PHXI12:THERMODYNAMICS
371306
Assertion : A reversible engine working between \(127^{\circ} \mathrm{C}\) and \(227^{\circ} \mathrm{C}\) cannot have efficiency more than \(20 \%\). Reason : Under ideal conditions \(\eta=1-\left(T_{2} / T_{1}\right)\).
1 Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
\({T_1} = 227 + 273 = 500\;K\) \({T_2} = 127 + 273 = 400\;K\) \(\eta_{\text {max }}=1-\dfrac{T_{2}}{T_{1}}=1-\dfrac{400}{500}=0.2\) \(\eta_{\max }=20 \%\) (As this is maximum, Assertion is true). So correct option is (1).
371302
If the temperature of a source increases, the efficiency of a heat engine
1 Increases
2 Decreases
3 Remains unchanged
4 None of these
Explanation:
Conceptual Question
PHXI12:THERMODYNAMICS
371303
An ideal heat engine working between temperatures \(T_{H}\) abd \(T_{L}\) has efficiency \(\eta\). If both the temperature are raised by \(100\;K\) each, the new efficiency of the heat engine will be:
1 Equal to \(\eta\)
2 Greater than \(\eta\)
3 Less than \(\eta\)
4 Greater or less than \(\eta\) depending upon the nature of the working substance
371304
If heat \(Q\) is added reversibly to a system at temperature \(T\) and heat \(Q^{\prime}\) is taken away from it reversibly at temperature \(T^{\prime}\), then which one of the following is correct
3 \(\dfrac{Q}{T}-\dfrac{Q^{\prime}}{T^{\prime}}=\) change in internal energy of the system
4 \(\dfrac{Q}{T}-\dfrac{Q^{\prime}}{T} < 0\)
Explanation:
In a reversible cycle \(\dfrac{Q}{T}=\dfrac{Q^{\prime}}{T^{\prime}}\)
PHXI12:THERMODYNAMICS
371305
A motor cycle engine delivers a power \(10\;kW\), by consuming petrol at the rate of \(2.4\;kg/hour\). If the calorific value of petrol is \(35.5\,MJ/kg\), the rate of heat rejection by the exhaust is
1 \(13.7\;kW\)
2 \(5.5\;kW\)
3 \(9.7\;kW\)
4 \(11.2\;kW\)
Explanation:
Heat received (or produced by the burning of petrol) in hour will be \( = (2.4\;kg/{\rm{ }}hour{\rm{ }})(35.5\,MJ/kg)\) \( = 85.2 \times {10^6}\;J/hour\) \(\therefore\) The rate at which heat is received \( = \frac{{85.2 \times {{10}^6}\;J}}{{(3600\;s)}} = 2.37 \times {10^4}\;J/s = 23.7\;k\,W\) The rate of heat rejection \(=\) rate at which heat is produced-rate at which work is done \( = 23.7\;k\,W - 10\;k\,W = 13.7\;k\,W\)
PHXI12:THERMODYNAMICS
371306
Assertion : A reversible engine working between \(127^{\circ} \mathrm{C}\) and \(227^{\circ} \mathrm{C}\) cannot have efficiency more than \(20 \%\). Reason : Under ideal conditions \(\eta=1-\left(T_{2} / T_{1}\right)\).
1 Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
\({T_1} = 227 + 273 = 500\;K\) \({T_2} = 127 + 273 = 400\;K\) \(\eta_{\text {max }}=1-\dfrac{T_{2}}{T_{1}}=1-\dfrac{400}{500}=0.2\) \(\eta_{\max }=20 \%\) (As this is maximum, Assertion is true). So correct option is (1).
371302
If the temperature of a source increases, the efficiency of a heat engine
1 Increases
2 Decreases
3 Remains unchanged
4 None of these
Explanation:
Conceptual Question
PHXI12:THERMODYNAMICS
371303
An ideal heat engine working between temperatures \(T_{H}\) abd \(T_{L}\) has efficiency \(\eta\). If both the temperature are raised by \(100\;K\) each, the new efficiency of the heat engine will be:
1 Equal to \(\eta\)
2 Greater than \(\eta\)
3 Less than \(\eta\)
4 Greater or less than \(\eta\) depending upon the nature of the working substance
371304
If heat \(Q\) is added reversibly to a system at temperature \(T\) and heat \(Q^{\prime}\) is taken away from it reversibly at temperature \(T^{\prime}\), then which one of the following is correct
3 \(\dfrac{Q}{T}-\dfrac{Q^{\prime}}{T^{\prime}}=\) change in internal energy of the system
4 \(\dfrac{Q}{T}-\dfrac{Q^{\prime}}{T} < 0\)
Explanation:
In a reversible cycle \(\dfrac{Q}{T}=\dfrac{Q^{\prime}}{T^{\prime}}\)
PHXI12:THERMODYNAMICS
371305
A motor cycle engine delivers a power \(10\;kW\), by consuming petrol at the rate of \(2.4\;kg/hour\). If the calorific value of petrol is \(35.5\,MJ/kg\), the rate of heat rejection by the exhaust is
1 \(13.7\;kW\)
2 \(5.5\;kW\)
3 \(9.7\;kW\)
4 \(11.2\;kW\)
Explanation:
Heat received (or produced by the burning of petrol) in hour will be \( = (2.4\;kg/{\rm{ }}hour{\rm{ }})(35.5\,MJ/kg)\) \( = 85.2 \times {10^6}\;J/hour\) \(\therefore\) The rate at which heat is received \( = \frac{{85.2 \times {{10}^6}\;J}}{{(3600\;s)}} = 2.37 \times {10^4}\;J/s = 23.7\;k\,W\) The rate of heat rejection \(=\) rate at which heat is produced-rate at which work is done \( = 23.7\;k\,W - 10\;k\,W = 13.7\;k\,W\)
PHXI12:THERMODYNAMICS
371306
Assertion : A reversible engine working between \(127^{\circ} \mathrm{C}\) and \(227^{\circ} \mathrm{C}\) cannot have efficiency more than \(20 \%\). Reason : Under ideal conditions \(\eta=1-\left(T_{2} / T_{1}\right)\).
1 Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
\({T_1} = 227 + 273 = 500\;K\) \({T_2} = 127 + 273 = 400\;K\) \(\eta_{\text {max }}=1-\dfrac{T_{2}}{T_{1}}=1-\dfrac{400}{500}=0.2\) \(\eta_{\max }=20 \%\) (As this is maximum, Assertion is true). So correct option is (1).
