JEE Main 2022 · PhysicsMultiple choiceSingle correctMediumCalculation

JEE Main 25 July 2022, Shift 2, Physics Q41

Question 41 of 90 in this shift, Physics question 11 of 30, Section A.

An electron with energy 0.1 keV moves at right angle to the earth's magnetic field of

1 \times 10^{-4}

Wbm

^{-2}

. The frequency of revolution of the electron will be (Take mass of electron =

9.0 \times 10^{-31}

kg)

(1) $1.6 \times 10^{5}$ Hz
(2) $5.6 \times 10^{5}$ Hz
(3) $2.8 \times 10^{6}$ HzOfficial answer
(4) $1.8 \times 10^{6}$ Hz

Official answer

Option 3

NTA final key.

Chapter: Moving Charges and Magnetism
Topic: Lorentz Force
Idea tested: Circular Motion in Uniform B-Field

Same idea in other shifts

Asked 7× in all

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25 Jul 2021, Shift 2 · Q14Two ions having same mass have charges in the ratio 1 : 2. They are projected normally in a uniform magnetic field with their speeds in…EasySingle correct
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9 Jan 2020, Shift 2 · Q14An electron gun is placed inside a long solenoid of radius $R$ on its axis. The solenoid has $n$ turns/length and carries a current $I$ .…MediumSingle correctHas a figure

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.