JEE Main 2021 · PhysicsMultiple choiceSingle correctEasyCalculation

JEE Main 18 March 2021, Shift 1, Physics Q8

Question 8 of 90 in this shift, Physics question 8 of 30, Section A.

A particle is travelling 4 times as fast as an electron. Assuming the ratio of de-Broglie wavelength of a particle to that of electron is 2 : 1, the mass of the particle is :

(1)8 times the mass of e $^-$
(2) $\frac{1}{16}$ times the mass of e $^-$
(3)16 times the mass of e $^-$
(4) $\frac{1}{8}$ times the mass of e $^-$ Official answer

Official answer

Option 4

NTA final key.

Chapter: Dual Nature of Radiation and Matter
Topic: Matter Waves
Idea tested: Wavelength Ratios of Different Particles

Same idea in other shifts

Asked 15× in all

4 Apr 2026, Shift 2 · Q44The de Broglie wavelength associated with an electron accelerated through a potential difference V is $\lambda_e$ and the de Broglie…EasySingle correct
8 Apr 2024, Shift 2 · Q46A proton and an electron have the same de Broglie wavelength. If $K_p$ and $K_e$ be the kinetic energies of proton and electron…EasySingle correct
1 Feb 2024, Shift 1 · Q46The de Broglie wavelengths of a proton and an $\alpha$ particle are $\lambda$ and $2\lambda$ respectively. The ratio of the velocities of…EasySingle correct
11 Apr 2023, Shift 2 · Q45The ratio of the de-Broglie wavelengths of proton and electron having same Kinetic energy : (Assume $\mathrm{m_p = m_e\times1849}$ )EasySingle correct
25 Jul 2022, Shift 2 · Q37The ratio of wavelengths of proton and deuteron accelerated by potential $\mathrm{V_p}$ and $\mathrm{V_d}$ is $1:\sqrt{2}$ . Then, the…EasySingle correct
25 Jun 2022, Shift 2 · Q46A proton, a neutron, an electron and an $\alpha$ -particle have same energy. If $\lambda_p, \lambda_n, \lambda_e$ and $\lambda_\alpha$ are…MediumSingle correct
27 Jun 2022, Shift 1 · Q43An $\alpha$ particle and a carbon 12 atom has same kinetic energy K. The ratio of their de-Broglie wavelengths…EasySingle correct
31 Aug 2021, Shift 1 · Q4A moving proton and electron have the same de-Broglie wavelength. If K and P denote the K.E. and momentum respectively. Then choose the…EasySingle correct

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.