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JEE Main
Exam
JEE Main
Subject
Physics
Chapter
Magnetic Properties of Matter

JEE Main · Physics · Magnetic Properties of Matter

The magnetization of bar magnet of length 5 cm, cross sectional...

The magnetization of bar magnet of length 5 cm, cross sectional area 2 cm2cm^{2} and net magnetic moment 1Am21Am^{2} is

Options

  1. A3×105Am3 \times \dfrac{{10}^{5}A}{m}
  2. B4×105Am4 \times \dfrac{{10}^{5}A}{m}
  3. C2×105Am2 \times \dfrac{{10}^{5}A}{m}
  4. D1×105Am1 \times \dfrac{{10}^{5}A}{m}

Correct answer

D. 1×105Am1 \times \dfrac{{10}^{5}A}{m}

Step-by-step solution

Given, l=5cm=5×10−2m,l = 5cm = 5 \times {10}^{- 2}m,
a=2cm2=2×10−4m2a = 2cm^{2} = 2 \times {10}^{- 4}m^{2}
And M=1Am−2M = 1Am^{- 2}
The magnetisation of the bar magnet is given by
l=MVl = \dfrac{M}{V}
where, V = volume of bar magnet = a×la \times l
⇒l=Ma×l⇒ l = \dfrac{M}{a \times l}
Substituting given values, we get
l=12×10−4×5×10−2=110−5l = \dfrac{1}{2 \times {10}^{- 4} \times 5 \times {10}^{- 2}} = \dfrac{1}{{10}^{- 5}}
=1×105Am= 1 \times \dfrac{{10}^{5}A}{m}
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