A hot electric iron has resistance of \( 88\,\Omega \) and is used with 220 V source. The electrical energy consumed in 4 h is
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → \( 7.92 \times 10^{6}\,\mathrm{J} \)
The electrical energy consumed is the power times the time, with the power of a resistor \( P = V^{2}/R \).
\( \displaystyle P = \frac{V^{2}}{R} = \frac{(220\,\mathrm{V})^{2}}{88\,\Omega} = \frac{48400}{88} = 550\,\mathrm{W} \)
\( \displaystyle t = 4\,\mathrm{h} = 4 \times 3600\,\mathrm{s} = 14400\,\mathrm{s} \)
\( \displaystyle W = P\,t = 550 \times 14400 = 7.92\times10^{6}\,\mathrm{J} \)