200 J of heat is produced each second in an 8 Ω resistance. Find the potential difference across the resistor.

H = 100 J, R = 4 Ω, t = 1 s, V =?

We have the current through the resistor as

$\mathrm{I}=\sqrt{(\mathrm{H}/\mathrm{R})\times \mathrm{t}}$

$\Rightarrow \mathrm{I}=\sqrt{(200/8)\times 1}$

$\Rightarrow \mathrm{I}=5 \mathrm{A}$

Thus, the potential difference across the resistor, V is

V = IR = 5 A × 8 Ω = 40 V.