JEE Main 2024 · PhysicsMultiple choiceSingle correctMediumMulti-step

JEE Main 8 April 2024, Shift 1, Physics Q42

Question 42 of 90 in this shift, Physics question 12 of 30, Section A.

Average force exerted on a non-reflecting surface at normal incidence is

2.4\times10^{-4}

N. If 360 W/cm

^2

is the light energy flux during span of 1 hour 30 minutes, Then the area of the surface is:

(1) $0.2\ \mathrm{m^2}$
(2) $0.1\ \mathrm{m^2}$
(3) $0.02\ \mathrm{m^2}$ Official answer
(4) $20\ \mathrm{m^2}$

Official answer

Option 3

NTA final key.

Chapter: Electromagnetic Waves
Topic: Thermal Radiation
Idea tested: Thermal Radiation Pressure

Same idea in other shifts

Asked 3× in all

3 Apr 2025, Shift 1 · Q40The radiation pressure exerted by a 450 W light source on a perfectly reflecting surface placed at 2m away from it, isMediumSingle correct
28 Jul 2022, Shift 2 · Q15Sun light falls normally on a surface of area $36\ \mathrm{cm^2}$ and exerts an average force of $7.2\times10^{-9}$ N within a time period…MediumSingle 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.