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 conductucing rod of length 1 moving with a velocity v towards left on a rectangular metallic framework as shown in Figure. The whole arrangement is placed in a uniform magnetic field `vec(B)` whose magnetic lines lines are perpendicular directed into the plane of the paper.
ii. As the rod moves from AB to DC in a time date,the area enclosed by the loop and hence the magnetic flux through the loop decreases.

iii. The change in magnetic flux in time dt is `dPhi_(B)=Bxx"change in are"`
`dPhi_(B)=Bxx"Area ABCD"`
Blvdt Since area ABCD = l (vdt)``(or)(dPhi_(B))/(dt)=Blv`
iv. 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)`
`epsilon=Blv`
v. This emf is called motional emf. The direction of induced current is found to be clockwise from Fleming's right hand rule.