Question

An $AC$ source is rated $220V,50Hz$. The average voltage, is calculated in a time interval of $0.01s$. It

• A. must be zero
• B. may be zero
• C. is never zero
• D. is $\left(220/\sqrt{2}\right)V$

Answer 1

The correct option is C is never zero

Time period of the AC source is $\tau =\frac{1}{50}=0.02s$.
Sum of instantaneous value of voltage over one cycle of AC source is zero. As the time interval in the question (0.01 s) is not an integral multiple of the time period $\tau$, the average value is never zero.