Question

A parallel plate capacitor is being charged by a constant current i. During the charging, the electric field within the plates is increasing with time.

Which one of the following statements concerning the magnetic field between the plates is true?


A) The magnetic field within a parallel plate capacitor is always equal to zero teslas.

B) The induced magnetic field is directed antiparallel to the increasing electric field.

C) The induced magnetic field strength has its largest value at the center of the plates and decreases linearly toward the edges of the plates.

D) At a given moment, the induced magnetic field strength has the same magnitude everywhere within the plates of the capacitor, except near the edges.

E) The induced magnetic field strength is zero teslas near the center of the plates and increases as r increases toward the edges of the plates.

Answer 1

E

Step-by-step explanation:

The parallel plate capacitor is being charged by a steady current i. If the constant current is flowing along a straight wire, what happens inside the capacitor, between the plates is that the induced magnetic field strength is zero Tesla near the center of the plates and increases as r increases toward the edges of the plates.

From Ampère–Maxwell law, the magnetic field between the capacitor plates assuming that the capacitor is being charged at a constant rate by a steady current is

B = μ₀r /2A
`(dQ)/(dt) e_(o)`

where;

μ₀ is permeability

Q(t) is the instantaneous charge on the positive plate,

A is the cross-sectional area of a plate and

e₀ is a unit vector