A dielectric slab of area `A` and thickness `d` is inderted between then plates of a capaitor of area `2A` with constant speed `upsilon` as shown in. Dustance between the plates is (d).
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The capacitor is connected to a battery of emf `E`. The current in the ciruit varies with time as.

Options

A.
B.
C.
D.

Answer

B

Explanation

`C=(Kepsilon_(0)ub)/d+(epsilon_(0)(l-u)b)/d,q=CV`
`I=(dq)/(dt)=V(dC)/(dt)=V[(Kepsilon_(0)bv)/d-(epsilon_(0)bv)/(d)]="constant"`
So till the dielectric is fully inserted, a constant current will flow. When the dielectric is fully insede, `C` will be vondyant, so `I=0`. And when dielectric starts coming out, again a constant current will flow but in opposite direction.
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