Identify the correct statements :
A. Effective capacitance of a series combination of capacitors is always smaller than the smallest capacitance of the capacitor in the combination.
B. When a dielectric medium is placed between the charged plates of a capacitor, displacement of charges cannot occur due to insulation property of dielectric.
C. Increasing of area of capacitor plate or decreasing of thickness of dielectric is an alternate method to increase the capacitance.
D. For a point charge, concentric spherical shells centered at the location of the charge are equipotential surfaces.
Choose the correct answer from the options given below :

Solution

Physics sir · 4 steps

Check each statement against one fact you already know, and only B fails: dielectrics do polarise.

1. Statement A. In series, 1/C_(eq) = 1/C₁ + 1/C₂ + …. Every term is positive, so 1/C_(eq) is larger than 1/Cₘᵢₙ alone, which makes C_(eq) smaller than the smallest capacitance. A is true.
2. Statement B. A dielectric has no free charges, but its bound charges still shift slightly inside each molecule. This polarisation creates surface charges that reduce the field and raise the capacitance. B is false.

   C = (Kε₀ A)/d

3. Statements C and D. From C = (Kε₀ A)/d, a larger plate area A or a thinner dielectric d both increase C, so C is true. For a point charge, V = kq/r depends only on r, so every sphere centred on the charge is an equipotential surface. D is true.
4. So. A, C and D are correct and B is wrong, which is option (a).

The idea to keep. Insulator means no free charges, not no displacement. Bound charges in a dielectric always shift a little, and that polarisation is exactly why a dielectric increases capacitance.

Answer from the NTA final answer key. Solution by PrepWiser.