Question

A thin metal plate P is inserted between the plates of a parallel-plate capacitor of capacitance C in such a way that its edges touch the two plates (figure 31-Q2). The capacitance now becomes
(a) C/2
(b) 2 C
(c) 0
(d) ∞.

Answer 1

(d) $\infty$

The thin metal plate inserted between the plates of a parallel-plate capacitor of capacitance C connects the two plates of the capacitor; hence, the distance d between the plates of the capacitor reduces to zero. It can be observed that the charges on the plates begin to overlap each other via the metallic plate and hence begin to conduct continuously.

Mathematically,
C = $\frac{{\in }_{0}A}{d}$
In this case, d = 0.
∴ C = $\infty$