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JEE Main 2021 · PhysicsMultiple choiceSingle correctMediumCalculation

JEE Main 17 March 2021, Shift 1, Physics Q18

Question 18 of 90 in this shift, Physics question 18 of 30, Section A.

An electron of mass m and a photon have same energy E. The ratio of wavelength of electron to that of photon is : (c being the velocity of light)

(1) $\left(\frac{E}{2m}\right)^{1/2}$
(2) $c\,(2mE)^{1/2}$
(3) $\frac{1}{c}\left(\frac{2m}{E}\right)^{1/2}$
(4) $\frac{1}{c}\left(\frac{E}{2m}\right)^{1/2}$ Official answer

Official answer

Option 4

NTA final key.

Chapter: Dual Nature of Radiation and Matter
Topic: Matter Waves
Idea tested: Matter Wave vs Photon Energy Scaling

Same idea in other shifts

Asked 2× in all

25 Feb 2021, Shift 2 · Q30The wavelength of an X-ray beam is 10 Å. The mass of a fictitious particle having the same energy as that of the X-ray photons is…MediumNumerical value

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.