Question

The phase difference between alternating current and emf is $\frac{\pi }{2}$. Which one of the following cannot be the constituent of the circuit?

• A. $C$ alone
• B. $R,L$
• C. $L,C$
• D. $R$ alone

Answer 1

Answer: (D)

$R$ alone

If the phase difference between $V$ and $I$ is $\frac{\pi }{2}$

$\therefore Power=V\cdot I=VI\cos \frac{\pi }{2}=0$

Since Power is $0$ it should only consists of reactive elements($L$ & $C$), Resistance $R$ cannot be present.