How will you induce an emf by changing the area enclosed by the coil? Induction of emf by changing the area of the coil:

Explanation

Consider a conducting rod of length 1 moving with a velocity v towards left on a rectangular metallic framework. The whole arrangement is placed in a uniform magnetic field `vecB` whose magnetic lines are perpendicularly directed into the plane of the paper. As the rod moves from AB to DC in a time dt, the area enclosed by the loop and hence the magnetic flux through the loop decreases.
The change in magnetic flux in time dt is
`dPhi_(B)=Bxxchang e` in area since Area ABCD = (vdt)

As a result of change in flux, an emf is generated in the loop. The magnitude of the induced emf is `epsilon=(dPhi_(B))/(dt)=Blv`
This emf is called motional emf. The direction of induced current is found to be clockwise from Fleming.s right hand rule.