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JEE Mains · Physics · STD 12 - 2. Electric potential and capacitance

A parallel plate capacitor has charge \(5 \times 10^{-6} \mathrm{C}\). A dielectric slab is inserted between the plates and almost fills the space between the plates. If the induced charge on one face of the slab is \(4 \times 10^{-6} \mathrm{C}\) then the dielectric constant of the slab is ________.

  1. A 10
  2. B 15
  3. C 5
  4. D 20
Verified Solution

Answer & Solution

Correct Answer

(C) 5

Step-by-step Solution

Detailed explanation

\(\begin{aligned} & \mathrm{Q}_{\mathrm{in}}=\mathrm{Q}\left(1-\frac{1}{\mathrm{~K}}\right) \\ & 4 \times 10^{-6}=5 \times 10^{-6}\left(1-\frac{1}{\mathrm{~K}}\right) \\ & 1-\frac{1}{\mathrm{~K}}=\frac{4}{5} \\ & \mathrm{~K}=5\end{aligned}\)