JEE Main 2020 · PhysicsMultiple choiceSingle correctMediumCalculation

JEE Main 2 September 2020, Shift 1, Physics Q13

Question 13 of 75 in this shift, Physics question 13 of 25.

A beam of protons with speed

4\times10^{5}\ \mathrm{ms^{-1}}

enters a uniform magnetic field of 0.3 T at an angle of

60^\circ

to the magnetic field. The pitch of the resulting helical path of protons is close to : (Mass of the proton

=1.67\times10^{-27}

kg, charge of the proton

=1.69\times10^{-19}

(1)2 cm
(2)5 cm
(3)4 cmOfficial answer
(4)12 cm

Official answer

Option 3

NTA final key (Sep 2020).

Chapter: Moving Charges and Magnetism
Topic: Lorentz Force
Idea tested: Helical Motion and Pitch

Same idea in other shifts

Asked 7× in all

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2 Sep 2020, Shift 2 · Q12The figure shows a region of length ‘ $l$ ’ with a uniform magnetic field of 0.3 T in it and a proton entering the region with velocity…MediumDiagram basedHas 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.