# Question #c11d1

May 25, 2017

See below.

#### Explanation:

Ac generator works on the principle of Electromagnetic induction .

consider the following Image .we know according to lenz law
$V \propto \frac{\mathrm{dp} h {i}_{b}}{\mathrm{dt}}$

hence there must be change in magnetic field in order to crate potential so , initially the loop is given a small torque as the arrow shown in the figure .

as the loop rotates in the magnetic field the force on the branch AB is shown by .

here the Force $\vec{F}$ is the force on electrons and hence the direction of motion of electrons in magnetic field . Now the electrons move from D to C to B to A but current moves in opposite direction which is A to B to C to D .

But wait , we have to see that in AC generator there are slip rings due to which when the loop completes one cycle it the direction of current changes , for instance .

in above figure if we start with ${90}^{o}$ and go till ${270}^{o}$ till that time A is negative and D is positive , but from ${270}^{o}$ to ${0}^{o}$ A becomes positive for that interval and D is negative for that interval .

In this way In one complete cycle it produces the AC current by different polarity of Terminal A and B .