Question

A current $I=I_0\sin \left(\omega t-\frac{\pi }{2}\right)$ flows in an AC potential of $E=E_0\sin$ to $t$ has been applied, then the power consumption in the circuit will be:

• A. $\frac{E_0}{I_0}\sqrt{2}$
• B. $\frac{EI}{\sqrt{2}}$
• C. $\frac{E_0}{I_0}2$
• D. zero

Answer 1

Answer: (D)

The rate of dissipation of energy in an electrical circuit is called power.
The power of an alternating current circuit depends upon the phase difference between the voltage and the current
$P=E_{rms}\times i_{rms}\times \cos \varphi$
For the given current and voltage variation,
phase difference is $90^{\circ }$.
The average power then is $P=E_{rms}\times i_{rms}\times \cos 90^{\circ }=0$
Hence, there is no energy dissipation in such a circuit.