question_answer

A Carnot's engine is made to work between \[200{{\,}^{o}}C\]and\[0{{\,}^{o}}C\]first and then between \[0{{\,}^{o}}C\]and \[-200{{\,}^{o}}C.\]The ratio of efficiencies of the engine in the two cases is:

A) \[1:1.73\]                            

B) \[1.73:1\]

C)  \[1:2\]                                 

D)  \[1:1\]

Correct Answer: A

Solution :

\[{{f}_{1}}=+\,8\,cm\] \[u=-12\,cm\] \[{{f}_{2}}=+\,6\,cm\] Image formed by converging lens is real and inverted. Hence \[\text{IInd}\]lens will produces real inverted and enlarged image.