Question

Each one of the following changes will increase emf (or voltage) in a simple generator except :

(a) increasing the number of turns in the armature coil

(b) winding the coil on a soft iron armature

(c) increasing the size of the gap in which the armature turns

(d) increasing the speed of rotation

Answer 1

By Faraday's Law, the voltage is proportional to the number of windings and the rate of the change in the magnetic field.
So you can add windings to move the magnet faster or use a stronger magnet at the same rate to increase the voltage.
Therefore, option (c), increasing the size of the gap in which the armature turns, is wrong.