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

Options

A. zero average current
B. 220 V average voltage
C. voltage and current out of phase by `90^(@)`
D. voltage and current possibly different in phase `phi` such that `|phi|lt pi/2`

Answer

A, D

Explanation

For house hold supplies, AC currents are used which are having zero average value over a cycle.
The line is having some resistance so power factor `cosphi=R/Z=0`
So, `phi=pi//2 rArr phi, lt pi/2`
i.e., phase the lies between 0 and `pi//2`.