Q.

A Carnot engine with efficiency 50% takes heat from a source at 600 K. In order to increase the efficiency to 70%, keeping the temperature of the sink same, the new temperature of the source will be                           [2023]

1 900 K  
2 300 K  
3 1000 K  
4 360 K  

Ans.

(3)

TL same

η=1-TLTH

50100=1-TL600

70100=1-TLTH

TL600=12, TLTH=310

TH=1000 K