A pulsed laser emits rectangular pulses of width 1 nanosecond at a repetition rate of 1 kHz. If the average power output is 1 mW, the average power over a single pulse duration, in Watts, is

The correct option is B 1000
Given that Laser emits rectangular pulse width of $1\text{nsec}$
Repetition rate of $1\text{kHz}$
If the average output power is $1\text{mW}$
Energy of each pulse is given by
$E=\frac{P_{\text{av}}}{R_{\text{rate}}}=\frac{1\times {10}^{-3}}{1\times {10}^3}=1\times {10}^{-6}\text{Joules}$
Power of each pulse $P_{\text{pulse}}=\frac{E}{\text{Duration of pulse}}$
$P_{\text{pulse}}=\frac{1\times {10}^{-6}}{1\times {10}^{-9}}=1000$