Question

An $\text{AC}$ source rated $100\text{V}\left(rms\right)$ supplies a current of $10\text{A}\left(rms\right)$ to a circuit. The average power delivered by the source is

• A. may be $1000\text{W}$
• B. may be less than $1000\text{W}$
• C. Both options $\left(A\right)$ and $\left(B\right)$
• D. may be greater than $1000\text{W}$

Answer 1

The correct option is C Both options $\left(A\right)$ and $\left(B\right)$

The average power delivered by the source is given by:

$P_{avg}=V_{rms}{I}_{rms}\cos \varphi$

Where $\cos \varphi$ is the power factor of the circuit.

Given, $V_{rms}=100\text{V}$ and $I_{rms}=10\text{A}$

$\Rightarrow P_{avg}=100\times 10\cos \varphi =1000\cos \varphi$

The value of $\cos \varphi$ lies between $[-1,1]$.

Therefore, power delivered by the source would be either equal to $1000\text{W}$ or less than $1000\text{W}$ depending on the elements connected in the circuit.

Hence, option $\left(C\right)$ is the correct answer.