How the direction of current changes in the armature coil of AC generators?

What is a dynamo? Describe an a.c. dynamo under the following headings:

$\left(\mathrm{ii}\right)$ Labelled diagram

Briefly explain working of a.c. generator.

What is a dynamo? Describe an a.c. dynamo under the following headings:

$\left(\mathrm{iii}\right)$ Working.

In a.c. generator induced emf at $\mathrm{t}=0$. the induced emf at the time $\frac{\pi }{\omega }$ is_____________.

With the help of a labelled diagram, derive the expression for instantaneous emf induced in an AC generator.

The phenomenon of electromagnetic induction has been technologically important application in the generation of alternating currents." Name the device which can generate alternating currents. Draw a neat diagram of it.

 A rectangular coil having an area vector $\overline{\mathrm{A}}$ and number of turns $\mathrm{N}$ is rotating in a magnetic field $\overline{\mathrm{B}}$ with angular speed $\omega$. If $\theta$be the angle made by the area vector $\overline{\mathrm{A}}$ with the field $\overline{\mathrm{B}}$ at time $t$. Derive an expression for alternating emf $\epsilon$ starting directly from Faraday's law. Draw a graph to show the generated e.m.f at the time   $0 ,\frac{\mathrm{T}}{4}.\frac{\mathrm{T}}{2},\frac{3\mathrm{T}}{4}\mathrm{and} \mathrm{T}$.