The plates of a parallel plate capacitor are charged up to `100 v`. Now, after removing the battery, a `2 mm` thick plate is inserted between the plates Then, to maintain the same potential deffernce, the distance betweem the capacitor plates is increase by `1.6 mm`. The dielectric canstant of the plate is .

Options

A. 5
B. `1.25
C. 4
D. 2.5

Answer

A

Explanation

Potential difference without dielectric, V = Ed and with dielectric
`V'=E(d'-t)+E't`
Hence, potential difference is same,
so
`Ed=E(d'-t)+E't`
`Exxd=E(d+1.6-2)+(E)/(K)xx2`
`d=d-0.4+(2)/(K)`
`implies" "K=5`