1.

A parallel - plate capacitor, filled with a dielectric of dielectric constant k, is charged to a potential V_0 .It is now disconnected from the cell and the slab is removed. If it now discharges, with time constant tau , through a resistance, then find time after which the potential difference across it will be V_0 ?

Answer»

SOLUTION :When the slab is removed , the potential difference ACROSS capacitor increases to `k V_0`
`CV_0 = kCV_0 e^(-t/tau) as q_0 = KCV_0`
`1/k = e^(-t/tau) THEREFORE ln k = t/tau RARR t= tau ln k `


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