Class 12th Physics 2017 Set2 Delhi Board Paper Solution

Question 26

Draw a labelled diagram of AC generator. Derive the expression for the instantaneous value of the emf induced in the coil. 

Answer

The labelled diagram of AC generator is as below:

Let at any moment t the perpendicular vector to the plane of coil makes angle θ with direction of magnetic field (B). So, flux passing through the coil

 φ  = Bcos θ. An

and θ = ωt

[ω is angular velocity of the coil]

So, φ  = n A B cos ωt 

If e is the instantaneous induced emf produced in the coil, then

Maximum value or peak value of e is attained when  sin ωt = ± 1

∴ emax = nω AB 

So,   e =   emax sin ωt 

Since, the value of the sine function varies between +1and −1. So, the polarity of emf changes with time and also, output voltage is sinusoidal in nature. 

Popular Questions of Class 12th physics

Recently Viewed Questions of Class 12th physics