A) is valid
B) is invalid
C) depends on engine design
D) depends on the load
Correct Answer: B
Solution :
The energy efficiency of a process is defined as \[\eta =\frac{power\text{ }output}{power\text{ }input}\] Power input\[=\frac{1g}{s}\times \frac{2k\,cal}{8}=2\text{ }k\text{ }cal/s\] Output energy\[=10\text{ }kW=10\text{ }kJ/s\] \[=\frac{10}{4.2}k\,cal/s\] \[\eta =\frac{10}{4.2\times 2}>1\] Since, energy efficiency is a dimensionless number, with a value between 0 to 1, or when multiplied by 100, is given as a percentage. Also, energy efficiency within a closed system can never exceed 100%, hence, claim of engineer is invalid.
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