A parallel plate capacitor made of circular plates is being charged such that the surface charge density on its plates is increasing at a constant rate with time. The magnetic field arising due to displacement current is:

Question

Question

This question was previously asked in

NEET 2025 Official Paper (Held On: 04 May, 2025)

zero at all places
constant between the plates and zero outside the plates
non-zero everywhere with maximum at the imaginary cylindrical surface connecting peripheries of the plates
zero between the plates and non-zero outside

Answer 1

Correct option is : (3) Non-zero everywhere with maximum at the imaginary cylindrical surface connecting peripheries of the plates

Let the surface charge density be σ = q / A

Given dq/dt = constant

⇒ d/dt (q / A) = constant ⇒ (1 / A) × dq/dt = constant

It means displacement current is constant.

This system will act like a cylindrical wire.

The graph of magnetic field (B) vs radius (r) is: