In a parallel plate capacitor of capacitance C, a metal sheet is inserted between the plates, parallel to them. The thickness of the sheet is half of the separation between the plates. The capacitance now becomes
Answer & explanation
Correct answer: option 2
Before the metal sheet is inserted, $C=\varepsilon_0 A / d$
After the sheet is inserted, the system is equivalent to two capacitors in series, each of capacitance C' = $\frac{\varepsilon_0 A}{d / 4}$ = 4C
The equivalent capacity is now 2C.
∴ (B)