Question

When a Ferromagnetic material is magnetized by alternating source voltage. The phenomenon of magnetostriation causes:
1. Increase in the body temperature
2. Change in permeability of the material
3. Small changes in its dimension
4. Decrease in the saturation flux density

Answer 1

Correct Answer - Option 3 : Small changes in its dimension

Magnetostriction:

• When a magnetic field is given to a magnetic material, it experiences an alteration in shape, or size, or length, or dimension. This property of some magnetic materials is known as magnetostriction.
• This change of dimension of magnetic materials during magnetization may continue till the magnetic saturation of the material is attained.
• This effect is the reason for the humming sound that we hear in the transformer.

Formula:

Magnetostriction can be calculated by the magnetostriction coefficient or Joule’s magnetostriction coefficient (λ).

λ = ∂ L / L

L = Length of the ferromagnetic material

∂ L = Change in the length of the material