An ac voltage is represented by E=220√2 cos(50π)t How many times will the current becomes zero in 1 s?
50 times
100 times
30 times
25 times
E=E0 cos ωt ∴ω=50π 2πf=50π⇒f=25 Hz In one cycle ac current becomes zero twice. Therefore, 50 times the current becomes zero in 1 s
The frequency of a source of sound is 100 Hz. How many times does it vibrate in a minute?