Correct Answer - Option 3 : Small changes in its dimension
- 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.
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