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Thermodynamics — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysicsThermodynamics4 Marks
Question
Read the passage given below and answer the following questions from (i) to (v) Carnot principles are only for the cyclical devices like heat engines, which state that the efficiency of an irreversible heat engine is always less than the efficiency of a reversible one operating between the same two reservoirs. The efficiencies of all reversible heat engines operating between the same two reservoirs are the same.
  1. In a Carnot cycle, the working medium rejects heat at a ________ temperature.
    1. Higher
    2. Lower
    3. constant
    4. none of these
  2. Which of the following is NOT a state variable?
    1. work
    2. internal energy.
    3. entropy
    4. all of the above
  3. The efficiency of reversible heat engine is:
    1. $1 +(T_2/T_1)$
    2. $(T_1/T_2)+1$
    3. $(T_1 /T_2)- 1$
    4. $1 - (T_2 / T_1)$
  4. Other factors remaining constant, if the temperature of the source is increased, the efficiency of the Carnot engine will:
    1. decrease
    2. increase
    3. constant
    4. increase or decrease depending upon temperature ratio
  5. Over the complete Carnot cycle, entropy:
    1. increase
    2. decrease
    3. constant
    4. first increase and then decrease
✓

Answer

  1. (b) lower
  2. (a) Work
  3. (d) $1- (T_2/ T_1)$
  4. (b) increase
  5. (c) constant

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