Name: Production of Induced EMF by Rotating the Loop
Uploaded: 2019-07-19
Duration: 13 min 16 s
Description: Learn how the magnetic flux can be altered by rotating a coil in a magnetic field such that the angle between the magnetic field and the area vector changes.

Question

Explain what is eddy current. Discuss its advantages and disadvantages. Suggest ways to minimize eddies in conducting blocks.

Accepted Answer

Eddy currents are loops of electrical current induced within conductors by a changing magnetic field in the conductor according to Faraday's law of induction. Eddy currents flow in closed loops within conductors, in planes perpendicular to the magnetic field. They can be created when a conductor is moving through a magnetic field, or when the magnetic field surrounding a stationary conductor is varying i.e. anything which results in the conductor experiencing a change in the intensity or direction of a magnetic field can produce eddy currents. The size of the eddy current is proportional to the size of the magnetic field, the area of the loop and the rate of change of magnetic flux, and inversely proportional to the resistivity of the conductor.

Advantages of eddy currents:

1.One of the most common methods is to use eddy currents to see whether a material or surface has any discontinuities, fractures, or faults without harming the material.
2. When an eddy current comes into close contact with a conductive or magnetic material, electromagnetic damping is automatically produced. When an eddy current interacts with another magnetic field, it causes electromagnetic damping.

Disadvantages:

1. Eddy currents, when generated, dissipate electrical energy in the form of heat.

2. These lead to overheating of metallic cores of transformers, electric motors and other such devices.

Eddy currents can be minimised by following ways:

1. Eddy currents are minimised in these devices by selecting magnetic core materials that have low electrical conductivity.

2. By increasing the resistance of the core:
The laminations are thin and have relatively high resistance, thus in transformers, the thin sheets of steel in the core should be insulated from each other by a thin layer of varnish. The planes of these sheets are arranged parallel to the magnetic fields so that they can cut across the path of the eddy current. This arrangement reduces the strength of the eddy currents. Since the dissipation of electrical energy into heat depends on the square of the strength of electric current, heat loss is substantially reduced.Tiny eddy currents still exist, but only within each thin sheet, so their entire effect is substantially small..

Explain what is eddy current. Discuss its advantages and disadvantages. Suggest ways to minimize eddies in conducting blocks.

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