JEE Main 2022 · PhysicsMultiple choiceSingle correctMediumCalculation

JEE Main 26 July 2022, Shift 1, Physics Q34

Question 34 of 90 in this shift, Physics question 4 of 30, Section A.

A parallel beam of light of wavelength 900 nm and intensity

100\ \mathrm{Wm^{-2}}

is incident on a surface perpendicular to the beam. The number of photons crossing

1\ \mathrm{cm^2}

area perpendicular to the beam in one second is :

(1) $3\times10^{16}$
(2) $4.5\times10^{16}$ Official answer
(3) $4.5\times10^{17}$
(4) $4.5\times10^{20}$

Official answer

Option 2

NTA final key.

Chapter: Dual Nature of Radiation and Matter
Topic: Photoelectric Effect
Idea tested: Photon Flux and Beam Power

Same idea in other shifts

Asked 7× in all

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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.