Question

The voltage of clouds is $4\times 10^{6} \, V$ with respect to ground. In a lightning strike lasting $\text{100 ms}$ , a charge of $\text{4 C}$ is delivered to the ground. The average power of lightning strike is (assume complete discharges )

• A. $\text{160 MW}$
• B. $\text{80 MW}$
• C. $\text{20 MW}$
• D. $\text{500 KW}$

Answer 1

Answer: (B)

Energy stored between cloud and earth, assuming the capacitor model is
$W=\frac{qV}{2}$
$\frac{4 \times 10^{6} \times 4}{2}=8\times 10^{6} \, J$
The power of lightning strike is
$P=\frac{W}{t}=\frac{8 \times 10^{6}}{0.1}=80\times 10^{6} \, W$
$ \, =80 \, MW$