CBSE Class 12 · 2023 · Magnetic Effects of CurrentLong Answer

Briefly explain the various ways to increase the strength of the magnetic field produced by a given solenoid.

Answer: Insert a soft-iron core, increase the number of turns per unit length, and increase the current.

Solution

The field inside a long solenoid is

B = μ_{0} n I

(and

μ_{0} μ_{r} n I

with a core), so its strength can be raised by:

Placing a soft-iron core inside the solenoid, which increases the permeability ( $μ_{r} ≫ 1$ ) and so the field.
Increasing the number of turns per unit length $n$ of the winding.
Increasing the current $I$ passed through the solenoid.

CBSE Class 12 Board · 2023 · Subjective