Question

An electric heater of resistance $6\Omega$ is run for $10min$ on a $120V$ line. The energy liberated in this period of time is

• A. $7.2\times 10^{3}J$
• B. $14.4\times 10^{5}J$
• C. $43.2\times 10^{4}J$
• D. $28.8\times 10^{4}J$

Answer 1

Answer: (B)

If $P$ represents power and $t$ represents time then the formula for energy is $E=P\times t$ $\Rightarrow E=\frac{V^2}{R}\times t$ $E=\frac{{\left(120\right)}^2}{6}\times 10\times 60J$ $=14.4\times 10^{5}J$