How to determine the polarities of inductor?
I know it is determined from Lenz law but most of the time i get a wrong answer,can anyone demonstrate how it is got, through an example?
Suppose that the current though the coil is increasing.
This means that the magnetic field inside the coil is increasing.
Lenz tells you that the induced current will try and oppose the charge producing it which is the increasing current.
So the induced current must be in the opposite direction to the current producing the change, the increasing current.
So the induced current will be going out of the coil on the left-hand side and into the coil on the right hand side.
So as far as the circuit outside the coil is concerned due to the induced current the right hand end of the coil is negative and the left hand end is positive.