Question

The magnetic field (B) inside a long solenoid having 'n', turns per unit length and carrying current 'I' when iron core is kept in it is (`mu_0` = permeability of vacuum, `chi` = magnetic susceptibility) ____________.

Options

• `mu_0  "nI"  (1 - chi)`

• `mu_0  "nI" chi`

• `mu_0   "nI"^2 (1 + chi)`

• `mu_0  "nI"  (1 + chi)`

Answer 1

The magnetic field (B) inside a long solenoid having 'n', turns per unit length and carrying current 'I' when iron core is kept in it is `mu_0  "nI"  (1 + chi)`.

Explanation:

Magnetic field inside a solenoid is given by,

`"B" = mu  "n I"`

`= mu_0  mu_"r"  "n I"`

` = mu_0  (1 + chi) "n I"`