Target Exam

CUET

Subject

Physics

Chapter

Electrostatic Potential and Capacitance

Question:

Identify the incorrect statement(s) among the following:

When a dielectric medium is introduced between the plates of a charged capacitor the electric field inside the dielectric changes due to polarisation. $E_0$ is the electric field between the plates of capacitor without dielectric and $E_p$ is the electric field due to polarisation.

(A) If a plate of dielectric constant k, thickness t is placed between the plates of a charged capacitor of area A of the plate and having distance d between the plates, then the new capacitance will be $Aε_0/(d-t(1+1/k))$
(B) The electric field between plates of the charged capacitor when the dielectric is introduced will be $E=(E_0-E_p)$
(C) Dilectric constant of the dielectric placed between plates of charged capacitor will be $k = E_0/(E_0-E_p)$
(D) Dielectric strength of the dielectric is the maximum value of the electric field which may be applied before its break down,

Choose the correct answer from the option given below:

Options:

(A) only

(B) and (D) only

(C) only

(A) and (D) only

Correct Answer:

(A) only

Explanation:

The correct answer is Option (1) → (A) only

(A) Incorrect — The correct formula for capacitance with a dielectric slab of thickness t and dielectric constant k partially filling the capacitor is more complex; the given formula $C = \frac{A\epsilon_0}{d - t(1+1/k)}$ is incorrect.

(B) Correct — Electric field inside dielectric $E = E_0 - E_p$ due to polarisation.

(C) Correct — Dielectric constant $k = \frac{E_0}{E_0 - E_p}$

(D) Correct — Dielectric strength is the maximum electric field before breakdown.

Incorrect statement: (A)