Question

The magnetic field inside a long solenoid having 50turns/cm is increased from 2.5 x 10^-3T to 2.5T when an iron core of cross-sectional area 4cm² is inserted into it. Find (a) the current in the solenoid, (b) the magnetization I of the core and (c) the pole strength developed in the core.

Answer 1

B₁ = 2.5 × 10^–3, B₂ = 2.5

A = 4 × 10^–4m², n = 50turns/cm = 5000turns/m

(a) B = μ₀ni,

=> 2.5 × 10^–3 = 4π × 10^–7 × 5000 × i

= 1.99 × 10⁶ ≈ 2 × 10⁶