| Previous Year Questions of March Examinations from 2010 to 2020 |
| Chapter Name: THERMODYNAMICS |
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Thermodynamics deals with the concept of heat and the exchange of heat energy. a) Which law of thermodynamics is used to explain the working of heat engine? b) What are the sink, source and working substances of a domestic refrigerator? c) Explain briefly, the operations of a Carnot’s engine draw the Carnot’s cycle and deduce the expression for its efficiency. OR a) Which thermodynamics process is also called an isoentropic process? b) The efficiency of a Carnot engine is 1/6 .If one reducing the temperature of the sink by 650C, its efficiency becomes 1/3 ,find the temperature of the sink and the source. c) Obtain the expression for the work done during an adiabatic process. |
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a) Isothermal, Isobaric, isochoric and adiabatic processes are some special thermodynamic processes. In which of these processes, the work done is maximum, when a gas expands from V1 to V2 ? b) Which law of thermodynamics implies that no heat engine can be 100% efficient? c) One mole of an ideal gas expands from volume V1 to volume V2 at a constant temperature T. Derive an expression for the work done. |
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A heat engine is a device which converts heat energy into work. a) What is the working substance in an ideal heat engine? b) Draw the Carnot cycle and explain its working. c) Calculate the efficiency of an engine working between steam point and ice point. Can you design an engine of 100 % efficiency? |
| Figure given depicts the schematic representation of an engine. a) Which type of engine is this, a heat engine or a refrigerator? b) Write the four steps of operation in the Carnot cycle. c) A Carnot engine is working between temperatures of 270 C and 3270 C . Find it efficiency. |
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“No real gas is truly ideal”. a) When does a real gas approach ideal gas behaviour? b) Define the law of equipartition of energy. |
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The variables which determine the thermodynamic behaviour of a system are called thermodynamic variables. a) Pick out the one which is NOT a thermodynamic variable. (temperature, pressure, work, volume) b) What happens to the internal energy of a gas during i) isothermal expansion? ii) adiabatic expansion? c) Gases have two specific heat capacities, CP and CV. Why? d) Laplace pointed out that when sound is propagating through a gaseous medium, the change is adiabatic. Show that adiabatic bulk modulus is γP . |
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a) Heat engine is a device used to convert........ energy into .......energy. b) Name the four processes taking place in Carnot cycle. Draw indicator diagram of Carnot cycle. |
| “Two systems in thermal equilibrium with a third system, are in thermal equilibrium with each other”. Identify the law given by the above statement |
Match the following in three columns
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The branch of Physics, that was developed to understand and improve the working of heat
engines is a) Optics b) Thermodynamics c) Electronics d) Electrodynamics |
| Schematic diagram of a device is shown in the figure a) Write the equation for the efficieney of the device b) Write the name of the four process in the working cycle of the device c) If T1 = 100°C, T2 = 0°C and Q1 = 4200 J, find the value of Q2 |
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| State first law of thermodynamics |
| Draw a graph showing the variation of volume of a given mass of water with temperature from 0°C. In the graph mark the temperature at which water has maximum density |
| Schematic diagram of a heat engine is shown a) Modify the given diagram for a refrigerator b) Write the equation for the coefficient of performance of a refrigerator c) In the given diagram, T1 =900K, T2 =300K, Q1 = 6400J / cycle calculate the value of Q2 |
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| Observe the given figure. (a) Is this a heat engine or refrigerator ? (b) Write the 4 steps of operation in the Carnot cycle. |
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| A refrigerator is to maintain eatables kept inside at 9 °C. If room temperature is 36 °C, calculate the coefficient of performance. |
| Write perfect gas equation |
| What is the difference between isobaric process and isochoric process ? |
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(a) What is the difference between latent heat of fusion and latent heat of vaporization ? (b) Why burns from steam are usually more serious than those from boiling water ? |
