MCQ 11 Mark
Assertion (A): If the frequency of the applied AC is doubled, then the power factor of a series R-L circuit decreases.
Reason (R): Power factor of series R-L circuit is given by \$\cos \phi=\frac{2 R}{R^2+\omega^2 L^2}$
Reason (R): Power factor of series R-L circuit is given by \$\cos \phi=\frac{2 R}{R^2+\omega^2 L^2}$
- ABoth A and R are true and R is the correct explanation of A.
- BBoth A and R are true but R is not the correct explanation of A.
- CA is true but R is false.
- DA is false but R is true.
Answer
View full question & answer→(c) A is true but R is false.
Explanation: $\cos \phi=\frac{R}{Z}=\frac{R}{\sqrt{R^2+\omega^2 L^2}}$
When $\omega$ is doubled, power factor $(\cos \phi)$ decreases.
So, A is true but R is false.
Explanation: $\cos \phi=\frac{R}{Z}=\frac{R}{\sqrt{R^2+\omega^2 L^2}}$
When $\omega$ is doubled, power factor $(\cos \phi)$ decreases.
So, A is true but R is false.