# Question regarding displacement current

• utkarshakash
In summary, displacement current arises due to a changing electric field and is not affected by a changing magnetic field. The induced electric field from a changing magnetic field may contribute to displacement current, but it is not a defining factor.
utkarshakash
Gold Member

## Homework Statement

Displacement current arises due to
a)changing electric field
b)changing magnetic field
c)both

## The Attempt at a Solution

I think the answer should be c) because we already know that changing electric field is responsible for displacement current. But if the magnetic field is also time-dependent then it will induce an electric field according to Faraday's law. So, the induced electric field will also contribute to the displacement current.
However, the correct answer is a).

Others are in a far better position than I to discuss your theory, but I would make 2 comments. (1) The voltage induced in a single turn (?) of an insulating material (the dielectric) by the capacitor's charging current may be minscule. (2) Consider the special case: if you were to charge the cap from a constant-current source, the charging current would be constant and unchanging, so with di/dt =0 there would be no induced voltages anywhere.

NascentOxygen said:
Others are in a far better position than I to discuss your theory, but I would make 2 comments. (1) The voltage induced in a single turn (?) of an insulating material (the dielectric) by the capacitor's charging current may be minscule. (2) Consider the special case: if you were to charge the cap from a constant-current source, the charging current would be constant and unchanging, so with di/dt =0 there would be no induced voltages anywhere.

I'm sorry but it's still not clear to me.

Hey!

Remember that the current displacement is only defined by the change in your polarization and your change in electric field, both with respect to time.

The magnetic field has no effect on this value.

This may seem counterintuitive, but displacement current is actually a purely electric phenomenon, despite its name. It is not related to the magnetic field or Faraday's law. It arises from the time-varying electric field itself, as described by Maxwell's equations. So, while a changing magnetic field can induce an electric field, this induced electric field is not considered displacement current. Therefore, the correct answer is a) changing electric field.

## 1. What is displacement current?

Displacement current is an electrical phenomenon that occurs when a changing electric field creates a magnetic field, even in the absence of a conductive medium. It is described by James Clerk Maxwell's equations of electromagnetism and is a crucial concept in understanding electromagnetic waves.

## 2. How is displacement current different from conduction current?

Displacement current is a time-varying electric field that produces a magnetic field, while conduction current is the movement of electrically charged particles through a conductive medium. Displacement current only occurs in non-conductive materials, while conduction current occurs in both conductive and non-conductive materials.

## 3. What is the significance of displacement current?

Displacement current plays a crucial role in the development of electromagnetic theory and is necessary to explain the behavior of electromagnetic waves. It also helps to understand the relationship between electric and magnetic fields, and how they interact with each other.

## 4. How is displacement current related to Maxwell's equations?

Displacement current is one of the four equations in Maxwell's equations that describes the relationship between electric and magnetic fields. It is represented by the term ∂D/∂t, where D is the electric displacement field. This equation helps to explain the behavior of electromagnetic waves and their propagation through space.

## 5. Can displacement current be measured?

Displacement current cannot be directly measured, but its effects can be observed through various experiments and measurements. It is an important theoretical concept that helps to explain the behavior of electromagnetic waves and is essential in the study of electromagnetism.

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