Question

A bar magnet is demagnetized by inserting it inside a solenoid of length 0.2 m, 100 turns, and carrying a curent of 5.2 A. The coercivity of the bar magnet is:

• A. 2600 A/m
• B. 520 A/m
• C. 285 A/m
• D. 1200 A/m

Answer 1

Answer: (A)

$\text{Given}$:Length of solenoid l = 0.2 m

No. of turns N = 100

Current I = 5.2 A

$\text{To find}$ : Coercivity of bar magnet H

$\text{Solution}$ :

Coercivity of bar magnet H = nI

Now, n = $\frac{N}{l}$

Therefore, H = $\frac{N}{l}\times I$ = $\frac{100}{0.2}\times 5.2$ = 26$\times 100$ = 2600

H = 2600 A/m

$\text{Hence A is the correct option}$