Question

In an ac circuit, V and I are given by

V = 100 sin (100 t) volts, $I = 100 \sin \left( 100 t + \frac { \pi } { 3 } \right) m A$.

The power dissipated in circuit is

• A. 10⁴ watt
• B. 10 watt
• C. 2.5 watt
• D. 5 watt

Answer 1

Answer: (C)

2.5 watt

Answer 2

$= \frac { 100 } { \sqrt { 2 } } \times \frac { 100 \times 10 ^ { - 3 } } { \sqrt { 2 } } \times \cos \frac { \pi } { 3 }$

$= \frac { 10 ^ { 4 } \times 10 ^ { - 3 } } { 2 } \times \frac { 1 } { 2 } = \frac { 10 } { 4 } = 2.5 \mathrm { watt }$