Join the Most Relevant JEE Main 2025 Test Series & get 99+ percentile! Join Now
Search any question & find its solution
Question: Answered & Verified by Expert
In an ac circuit, the power factor
PhysicsAlternating CurrentJEE Main
Options:
  • A Is zero when the circuit contains an ideal resistance only
  • B Is unity when the circuit contains an ideal resistance only
  • C Is unity when the circuit contains an ideal inductance only
  • D Is unity when the circuit contains an ideal inductance only
Solution:
1264 Upvotes Verified Answer
The correct answers are: Is unity when the circuit contains an ideal resistance only
Power factor, $\cos \phi=\frac{R}{Z}$
When circuit contains only resistance, then
$\begin{aligned}
& \mathrm{Z}=\mathrm{R} \\
& \therefore \cos \phi=1
\end{aligned}$
When circuit contains only inductance, then
$\begin{aligned}
& \mathrm{R}=\mathrm{o} \\
& \therefore \cos \phi=\mathrm{o}
\end{aligned}$

Looking for more such questions to practice?

Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.