JEE Main 2015PhysicsMagnetic Properties of MatterMediumMCQ

JEE Main 2015 — Magnetic Properties of Matter Question with Solution

JEE Main 2015 (11 Apr Online)

Question

A short bar magnet is placed in the magnetic meridian of the earth with North Pole pointing north. Neutral points are found at a distance of 30 cm from the magnet on the East-West line, drawn through the middle point of the magnet. The magnetic moment of the magnet in Am2 is close to:

(Given μ04π=10-7 in SI units and BH= Horizontal component of earth's magnetic field =3.6×10-5 Tesla.)

Choose an option

Show full solutionCorrect option: D
Correct answer
D9.7

Step-by-step explanation

Horizontal component of earth's magnetic field is along geographical south its North.

M→= Magnetic dipole moment.



At neutral point on the equatorial line the magnetic field B′ cancels BH

∴B′=BH

⇒μ04πMx3=BH 

⇒10-7×M301003=3.6×10-5

⇒10-7×103×M27=3.6×10-5

M=27×3.6×10-510-4

M=27×3.6×10-1

=9.72

M≈9.7

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About this question

This is a previous-year question from JEE Main 2015, covering the Magnetic Properties of Matter chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.