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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