Correct Answer - Option 3 : Small changes in its dimensions
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
