NEETPhysicsElectromagnetic Waves
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): For a charging circular parallel plate capacitor, the induced magnetic field at the central axis connecting the plates is zero. Reason (R): The displacement current density is zero at the central axis of the capacitor. In the light of the above statements, choose the most appropriate answer from th
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A)
- BBoth (A) and (R) are correct but (R) is not the correct explanation of (A)
- C(A) is correct but (R) is not correct
- D(A) is not correct but (R) is correct
Correct answer
C. (A) is correct but (R) is not correct
Step-by-step solution
Assertion (A) is correct: According to the Ampere-Maxwell law, B d l = ₀ I_ d, enclosed . At the central axis ( r = 0 ), an Amperian loop encloses zero area, meaning the enclosed displacement current is zero. Hence, the induced magnetic field B is zero. Reason (R) is incorrect: The changing electric field E is uniform across the entire area of the plates. Therefore, the displacement current density J_d = ₀ dE dt is uniform and non-zero everywhere between the plates, including at the central axis. Thus, (A) is corre