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Saturday, 31 October

JEE Main · Physics · Dual Nature of Radiation and Matter

Photon Flux and Beam Power

JEE Main asked Photon Flux and Beam Power 7 times in 6 of the 108 shifts Lumi analysed, in 2020, 2021, 2022 and 2024. It belongs to Photoelectric Effect, in Dual Nature of Radiation and Matter (Physics). The longest wait between two years asking it was 2 years. In 2021 and 2022 it came in more than one shift of the same year.

Updated 2026-10-24

Times asked
7
in 6 shifts
Years
4 of 8
First asked
2020
last in 2024
Pattern
Comes in cycles
across the analysed shifts

Questions on this idea a shift, by year

2017–2026. Asked in 2020, 2021, 2022 and 2024. Years differ in how many shifts Lumi analysed, so each year is scaled to one shift of 25 Physics questions.

00.050.10’170.08’200.10’210.07’220’230.05’240’250’26

Raw count: 2017: 0 in 1 shift · 2020: 1 in 12 shifts · 2021: 3 in 24 shifts · 2022: 2 in 24 shifts · 2023: 0 in 12 shifts · 2024: 1 in 18 shifts · 2025: 0 in 8 shifts · 2026: 0 in 9 shifts.

Shift by shift

Each square is one analysed shift, in date order. Open a filled one for that paper.

  • 20260 of 9
  • 20250 of 8
  • 20241 of 18
  • 20230 of 12
  • 20222 of 24
  • 202122 of 24
  • 20201 of 12
  • 20170 of 1

Asked in that shift More than once Not asked

How JEE Main framed it

Single correct is the usual form. Skill tested: calculation.

  • Photons emitted per second from power
  • Photon flux from intensity and wavelength

Difficulty

Easy 3Medium 4Hard 0

2 of the 7 questions had a numerical answer.

Every question

All 7 questions

From the official JEE Main shift papers, newest first. Open one for the full question, the options and the official answer.

  1. 1 Feb 2024, Shift 2 · Q46Monochromatic light of frequency 6×10146\times10^{14} Hz is produced by a laser. The power emitted is 2×10−32\times10^{-3} W. How many photons per…EasySingle correct
  2. 30 Jun 2022, Shift 1 · Q48A source of monochromatic light liberates 9×10209\times10^{20} photon per second with wavelength 600 nm when operated at 400 W. The number of…EasySingle correct
  3. 26 Jul 2022, Shift 1 · Q34A parallel beam of light of wavelength 900 nm and intensity 100 Wm−2100\ \mathrm{Wm^{-2}} is incident on a surface perpendicular to the beam.…MediumSingle correct
  4. 4 Aug 2021, Shift 2 · Q29A light source of 25.1 mW emits 2×10162 \times 10^{16} photons per second. An unknown metal is brought in front of this light source from…MediumNumerical value
  5. 4 Aug 2021, Shift 2 · Q53The number of photons emitted by a 800 nm lamp having an average power of 5 mW in 10 s is ________ × 1017\times\ 10^{17}. (Nearest integer)…EasyNumerical value
  6. 3 Aug 2021, Shift 1 · Q18An amount of 8×10208 \times 10^{20} photons per second are emitting from a monochromatic source of light operated at 500W, with 80%…MediumSingle correct
  7. 3 Sep 2020, Shift 2 · Q17Two sources of light emit X-rays of wavelength 1 nm and visible light of wavelength 500 nm, respectively. Both the sources emit light of…MediumSingle correct

Shifts: 3 Sep 2020, Shift 2, 3 Aug 2021, Shift 1, 4 Aug 2021, Shift 2, 30 Jun 2022, Shift 1, 26 Jul 2022, Shift 1, 1 Feb 2024, Shift 2.

Same topic

Other ideas in Photoelectric Effect

Photoelectric Effect has 15 ideas JEE Main has asked; 13 of them came up in more than one question. The 12 most asked are below.

Topic analysisChapter analysisStudy this chapterAll repeated ideas