Class 12 Physics
CBSE and UP Board
Magnetism and Matter
Chapter-5 Exercise 5.5
NCERT Solutions for Class 12 Physics Chapter 5 Question 5
A closely wound solenoid of 800 turns and area of cross section 2.5 × 10⁻⁴ m² carries a current of 3.0 A. Explain the sense in which the solenoid acts like a bar magnet. What is its associated magnetic moment?
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Number of turns in the solenoid, n = 800,
Area of cross-section, A = 2.5 x 10-4 m2
Current in the solenoid, I = 3.0 A
A current-carrying solenoid behaves as a bar magnet because a magnetic field develops along its axis, i.e., along its length.
The magnetic moment associated with the given current-carrying solenoid is calculated as:
M = n I A = 800 x 3 x 2.5 x 10-4 = 0.6 J T–1