Question

In each fission of ${}_{92}^{235}\text{U}$, 200 MeV energy is released. How many fissions must occur per second to produce power of $1kW$?

• A. $1.25\times {10}^{18}$
• B. $3.125\times {10}^{13}$
• C. $3.2\times {10}^{18}$
• D. $1.25\times {10}^{13}$

Answer 1

Answer: (B)

$3.125\times {10}^{13}$

$1kW={10}^{3}J{s}^{-1}$
$1MeV=1.6\times {10}^{-13}J$
Let $n$ be the fission/sec, each releasing 200 MeV.
$\therefore {10}^3=n\times 200\times 1.6\times {10}^{-13}$
$\therefore n=\frac{{10}^3}{200\times 1.6\times {10}^{-13}}=3.125\times {10}^{13}fission/sec$