A slab of copper of thickness b is inserted in between the plates of a parallel plate capacitor as shown in figure. The separation of the plates is d. If `b = d//2`, then the ratio of capacities of the capacitor after and before inserting the slab will be

Options

A. `1 : 1`
B. `1 :sqrt2`
C. `2 : 1`
D. `sqrt2 : 1`

Answer

A

Explanation

`C_(m)=(Ain_(0))/(d-t+t/k)`
`=(Ain_(0))/(d-d/2+t/oo)" ""for"" "C_(u),k=oo`
`=(Ain_(0))/(d/2)=(2Ain_(0))/d`
`C_(m)=2C_("air")`
`therefore" "C_(m)/C_("air")=2/1`