Question

What will happen when the frequency of rotation in an AC dynamo is doubled?

Answer 1

Induced voltage in the rotating loop is given by $E=NBAw\sin wt$
where $N$ is the number of turns in the loop, $A$ is the area of the loop, $B$ is the magnetic field and $w$ is the angular frequency of rotation of loop.
$⟹E\propto w$
So, the induced voltage gets doubled if the frequency of rotation of dynamo is doubled.
Also the frequency of the alternating current produced will also get doubled.