Electrical Engineering - Magnetism and Electromagnetism - Discussion

It is why because for one revolution means one complete cycle of the wave. It means for one complete wave there will be two half cycles.

In each half cycle it touches the peak once. So for one revolution 2 times and for 90 revolutions 180 times.

Each side of the coil will pass in front of the North pole two times/rev. (gives max output voltage in one direction) and will pass in front of the south pole two times/rev. (gives max. Output voltage in the opposite direction).

This means; output voltage will reach maximum two times in one rev.

Then output voltage will reach maximum 180 times in one second (2*90) = 180.

Nm = 90 * 60 = 5400 rev/min.
W=2π * Nm/60.

W= 2*3.14*5400/60 = 565 rad/second.
W= 2π*f.
F=W/2π.
F=565/2*3.14= 90,
Answer is 90.