A Carnot engine takes `3xx10^6cal`. of heat from a reservoir at `627^@C`, and gives it to a sink at `27^@C`. The work done by the engine is

Options

A. `4.2xx10^(6) J`
B. `8.4xx10^(6) J`
C. `16.8 xx10^(6) J`
D. zero

Answer

D

Explanation

`T_(1)=627+273=900K`
`Q_(1)=3xx10^(6) cal`
`T_(2)=27+273=300 K`
`:. (Q_(1))/(T_(1))=(Q_(2))/(T_(2))`
`Q_(2)=(T_(2))/(T_(1))xxQ_(1)=300/900xx3xx10^(6) =1xx10^(6) cal`
Work done `=Q_(1)-Q_(2)`
`=3xx10^(6)-1xx10^(6) =2xx10^(6)`
`=2xx4.2xx10^(6) J=8.4xx10^(6) J`