A bar magnet has a coercively 4× 103Am-1 . It is desired to demagnetize it by inserting it inside a solenoid 12 cm long and having 60 turns. The current carried by the solenoid should be:

Question

A bar magnet has a coercively 4× 103Am-1 . It is desired to demagnetize it by inserting it inside a solenoid 12 cm long and having 60 turns. The current carried by the solenoid should be: (A) 8 A (B) 6 A (C) 4.5 A (D) 2 A

Tardigrade Admin · Accepted Answer

The reversed magnetic field needed to demagnetise the specimen is known as coercivity of the material.

B = μ_{0} H

or

μ_{0} ni = μ_{0} H

or

\frac{N i}{L} = H

(∵ n = \frac{N}{L})

or

i = \frac{H L}{N}

Given,

H = 4 \times 10^{3} A m^{- 1},

L = 12 c m = 12 \times 10^{- 2} m, N = 60 t u r n s

. Substituting the values, we get

i = \frac{4 \times 10 ^{3} \times 12 \times 10 ^{- 2}}{60} = 8 A

Q. A bar magnet has a coercively 4×103Am−1 . It is desired to demagnetize it by inserting it inside a solenoid 12cm long and having 60 turns. The current carried by the solenoid should be:

8 A

6 A

4.5 A

2 A

The reversed magnetic field needed to demagnetise the specimen is known as coercivity of the material. B=μ0​H or μ0​ni=μ0​H or LNi​=H (∵n=LN​) or i=NHL​ Given, H=4×103Am−1, L=12cm=12×10−2m,N=60turns . Substituting the values, we get i=604×103×12×10−2​=8A

Q. A bar magnet has a coercively $4 \times 10^{3} A m^{- 1}$ . It is desired to demagnetize it by inserting it inside a solenoid $12 c m$ long and having $60$ turns. The current carried by the solenoid should be: