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JEE Main 2020 · PhysicsMultiple choiceSingle correctMediumMulti-step

JEE Main 9 January 2020, Shift 2, Physics Q18

Question 18 of 75 in this shift, Physics question 18 of 25, Section A.

An electron of mass

m

and magnitude of charge

|e|

initially at rest gets accelerated by a constant electric field

E

. The rate of change of de-Broglie wavelength of this electron at time

t

ignoring relativistic effects is :

(1) $\frac{-h}{|e|Et^2}$ Official answer
(2) $\frac{|e|Et}{h}$
(3) $-\frac{h}{|e|E\sqrt{t}}$
(4) $-\frac{h}{|e|Et}$

Official answer

Option 1

NTA final key (Jan 2020).

Chapter: Dual Nature of Radiation and Matter
Topic: Matter Waves
Idea tested: Time Rate of Change of Wavelength

Same idea in other shifts

Asked 2× in all

8 Apr 2025, Shift 2 · Q50An electron is released from rest near an infinite non-conducting sheet of uniform charge density ' $-\sigma$ ' .The rate of change of…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 42 of the 174 JEE Main shifts held from 2017 to 2026.