Question

The line that draws power supply to your house from street has

• A. Zero average current
• B. $220V$ average voltage
• C. Voltage and current out of phase by ${90}^{\circ }$
• D. Voltage and current possibly differing in phase $\varphi$ such that $|\varphi |<\frac{\pi }{2}$

Answer 1

Answer: (A), (D)

The correct options are
A Zero average current
D Voltage and current possibly differing in phase $\varphi$ such that $|\varphi |<\frac{\pi }{2}$

AC supply are used in houses.
So average current over a cycle of $AC$ is zero. In household circuit $L$ and $C$ are connected, so $R$ and $Z$ cannot be equal.
So, Power factor $=\cos \varphi =\frac{R}{Z}\ne 0$
as $\varphi \ne \frac{\pi }{2}\Rightarrow \varphi <\frac{\pi }{2}$
i.e. phase angle between voltage and current lies between $0$ and $\frac{\pi }{2}$.