2. Electric Potential and Capacitance
easy

A sheet of aluminium foil of negligible thickness is introduced between the plates of a capacitor. The capacitance of the capacitor

A

increases

B

decreases

C

Remains unchanged

D

becomes infinite

(AIEEE-2003)

Solution

Capacitance of parellel plate capacitor with a dielectric slab of thickness $t$ inside is given by:

$C =\frac{ A \epsilon_0}{( d – t )+\frac{ t }{ K }}$, where $K$ is the dielectric constant.

When aluminium sheet of negligible thickness is inserted, then thickness of slab $t \rightarrow 0$ and value of $K$ for metal (conductor) will be $\infty$

Therefore $C =\frac{ A \epsilon_0}{ d }$

Hence, capacitance of capacitor will remains unchanged.

Standard 12
Physics

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