Question 110: Magnetism and Matter

Question

The coercivity of a small magnet where the ferromagnet gets demagnetized is $3 	imes {10^3}\,A{m^{ - 1}}.$ The current required to be passed in a solenoid of length $10$ $cm$ and number of turns $100,$ so that the magnet gets demagnetized when inside the solenoid, is :

Accepted Answer

Magnetic field in solenoid $B = {\mu _0}ni$
$ \Rightarrow {B \over {{\mu _0}}} = ni$
(Where $n=$ number of turns per unit length)
$ \Rightarrow {B \over {{\mu _0}}} = {{Ni} \over L}$
$ \Rightarrow 3 	imes {10^3} = {{100i} \over {10 	imes {{10}^{ - 2}}}}$
$ \Rightarrow i = 3A$

Answer

$30$ $mA$

Answer

$60$ $mA$

Answer

$3$ $A$

Answer

$6A$

Magnetism and Matter

The coercivity of a small magnet where the ferromagnet gets demagnetized is 3 \times {10^3}\,A{m^{ - 1}}. The current required to be passed in a solenoid of length 10 cm and number of turns 100, so that the magnet gets demagnetized when inside the solenoid, is :

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