Question

An electric heater of resistance 6 ohm is run for 10 minutes on a 120 volt line. The energy liberated in this period of time is

• A. $7.2\mspace{6mu} \times \mspace{6mu} 10^{3}\mspace{6mu} J$
• B. $14.4 \times \mspace{6mu} 10^{5}\mspace{6mu} J$
• C. $43.2\mspace{6mu} \times \mspace{6mu} 10^{4}\mspace{6mu} J$
• D. $28.8\mspace{6mu} \times \mspace{6mu} 10^{4}\mspace{6mu} J$

Answer 1

Answer: (B)

$14.4 \times \mspace{6mu} 10^{5}\mspace{6mu} J$

Answer 2

By using $H = \frac{V^{2}t}{R}$

⇒ $H = \frac{(120)^{2} \times 10 \times 60}{6} = 14.4 \times 10^{5}J$