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1)

Consider a reversible engine of efficiency  16. When the temperature of the sink is reduced by 620C , its efficiency gets doubled. The temperature of the source and sink  respectively are


A) 372 K and 310 K

B) 273 K and 300 K

C) 990C and 100C

D) 2000C and 370C

Answer:

Option A

Explanation:

 Given

           η1=16

 According to the question,

η1=T1T2T1

 T1T2T1=16......(i)

η2=T1(T262)T12×η1=T1T2+62T1

2×16=T1T262T113=T1T2+62T1 .....(ii)

 from  Eq.(i) we ,get,

 T1T2=T16

 Substituting this value in Eq(11), we get

   13=T16+62T113=T1+3726T1

  6T1=3T1+11163T1=1116T1=372K

 From Eq.(i) , we get

      372T2372=16

 6(372T2)=372

 22326T2=372

   6T2=2232372

  6T2=1860

  T2=18606

    T2=310K