Question

The primary coil of a transformer has 250 turns and which is surrounded by a flux of 5mWb. When the magnet moves, the flux reduced into 3mWb. If it is connected to a 220-V line, find the time interval during which the flux changes.

Answer 1

As we all know, the voltage depends on the rate of change of magnetic flux and the number of turns:

$$V=N\dfrac{\Delta \Phi}{\Delta t}→\Delta t=\dfrac {N\Delta \Phi}V=2.27\text{ ms}.$$