Question

The coefficient of induction of a choke coil is 0.1H and resistance is$12 \Omega$. If it is connected to an alternating current source of frequency 60 Hz, then power factor will be

• A. 0.32
• B. 0.30
• C. 0.28
• D. 0.24

Answer 1

Answer: (B)

0.30

Answer 2

$\cos \phi = \frac { R } { Z } = \frac { R } { \sqrt { R ^ { 2 } + \omega ^ { 2 } L ^ { 2 } } }$

$= \frac { 12 } { \sqrt { ( 12 ) ^ { 2 } + 4 \times \pi ^ { 2 } \times ( 60 ) ^ { 2 } \times ( 0.1 ) ^ { 2 } } }$ $\Rightarrow \cos \phi = 0.30$