JEE Main 2022PhysicsMagnetic Properties of MatterMediumMCQ

JEE Main 2022 — Magnetic Properties of Matter Question with Solution

JEE Main 2022 (27 Jul Shift 2)

Question

A compass needle of oscillation magnetometer oscillates 20 times per minute at a place P of dip 30°. The number of oscillations per minute become 10 at another place Q of 60° dip. The ratio of the total magnetic field at the two places BQ:BP is:

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Show full solutionCorrect option: A
Correct answer
A3:4

Step-by-step explanation

At point P the needle oscillates 20 times per minute. Therefore, time period TP=6020= 3 s and at point Q, TQ=6010=6 s.

The time period of oscillation magnetometer is given by,

T=2πIBHM

⇒TP=3=2πIBPcos30°M

And TQ=6 s=2πIBQcos60°M

Taking ratio,

36=1 BP32×BQ2

⇒34=BQBP

⇒BQ:BP=3:4

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About this question

This is a previous-year question from JEE Main 2022, 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.