Question

An ac voltage is represented by $E=220\sqrt{2}cos\left(50\pi \right)t$ How many times will the current becomes zero in 1 s?

• A. 50 times
• B. 100 times
• C. 30 times
• D. 25 times

Answer 1

The correct option is A

50 times

$E=E_{0}cos\omega t$
$\therefore \omega =50\pi$
$2\pi f=50\pi \Rightarrow f=25Hz$
In one cycle ac current becomes zero twice.
Therefore, 50 times the current becomes zero in 1 s