Q. The efficiency of Car not engine is and temperature of is . If the temperature of source is kept constant and its efficiency is to be raised to , then the required temperature of the sink will be:

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Solution:

Efficiency of the Carnot engine is given by
(i)
where temperature of source
temperature of
Given,
Substituting in relation (i), we have or
or

Now, the temperature of sink is changed to
and the efficiency becomes
i.e, . Using relation (i), we get

or
or
Carnot engine is not a practical engine because many ideal situations have been assumed while designing this engine which can practically not be obtained.