Q 12-13-027JEE MainMedium
Each fission of U-235 releases about $200$ MeV. Find the number of fissions per second needed to produce $1$ W of power, in units of $10^{10}$. ($1$ MeV $= 1.6 \times 10^{-13}$ J; give one decimal place)
Numerical value type. Enter your answer.
Answer: 3.1
Concept. Fissions per second $= \dfrac{\text{power}}{\text{energy per fission}}$.
Step 1. Energy per fission. $200 \times 1.6 \times 10^{-13} = 3.2 \times 10^{-11}$ J.
Step 2. Rate.
$$\frac{1}{3.2 \times 10^{-11}} \approx 3.1 \times 10^{10}\ \text{s}^{-1}$$
Answer. $3.1$.
Solution by Sreeraj P, M.Sc Physics