Lakshya Education MCQs

Question: Now Tony settles upon a Carnot engine. Calculate the efficiency of the Carnot engine if the temperature it operates between are 350 K and 250 K.

Options:
A.27
B.57
C.37
D.47
E.along the line CD
Answer: Option A
: A

The efficiency of a Carnot engine is given by the formula ηH.E=1TLTH Substituting for known values we get ηH.E=1250350=27

Submit Answer & Explaination

Earn Reward Points by submitting Detailed Explaination for this Question

More Questions on This Topic :

Question 1. An ideal gas in a heat engine executes the cycle shown. Where is the temperature of the gas maximum?

  1.    along the line BC
  2.    at point B
  3.    at point C
  4.    at point D
  5.    along the line CD
Answer: Option C
: C

Temperature is maximum at point C. for ideal gas, pV = NRT, so T is max, when pV is max, which corresponds to the point furthest from the origin.
Question 2. Again, the engine does 41,000 J of useful work. If it sinks 9,000 J of energy in the form of heat to its cold reservoir, what is the efficiency of this engine?
  1.    18%
  2.    64%
  3.    82%
  4.    40%
Answer: Option C
: C

QH=W+QL=50000J e=EnergyoutputEnergyinput=WQH=41000J50000J=82or82%
Question 3. The figure here shows five paths traversed by a gas on a P-V diagram. Rank the paths according to the change in internal energy of the gas, greatest first.

  1.    5 > 4 = 3 > 2 = 1
  2.    5 > 4 = 3 > 1 = 2
  3.    4 = 3 > 5 > 1 = 2
  4.    5 > 4 = 3 = 2 = 1
  5.    along the line CD
Answer: Option D
: D

For any ideal gas, the internal energy can be related to the temperature as - Eint=nCvT ΔEint=nCvΔT (for a change of state). Thus the change in internal energy is solely dictated by the change in temperature.Since, all the processes 1, 2, 3, and 4 begin and end at the same temperatures, their ΔTs(and,ΔEint=nCv(T2T1)) are the same. Process 5, on the other hand goes through a larger ΔT(T3T1), hence gains the highest internal energy.

Check all Questions in this Topic : Click HERE