Q27.A 2 mW laser operates at a wavelength of 500 nm . The number of photons that will be emitted per second is: [Given Planck's constant h = 6.6 × 10-34 J s, speed of light c = 3.0 × 108 m / s ] (1) 1.5 × 1016 (2) 5 × 1015 (3) 2 × 1016 (4) 1 × 1016 JEE Main 2019 (10 Apr Shift 2) JEE Main Previous Year Paper
What This Question Tests
This question tests the ability to calculate the number of photons emitted per second by a laser given its power and wavelength, using the quantum energy relation.
Concepts Tested
Formulas Used
E = hc/λ
P = N * E / t
📚 NCERT Sections This Tests
11.4 — Monochromatic Light Of Wavelength 632.8 Nm Is Produced By A
Physics Class 12 · Chapter 11
11.4 Monochromatic light of wavelength 632.8 nm is produced by a helium-neon laser. The power emitted is 9.42 mW. (a) Find the energy and momentum of each photon in the light beam, (b) How many photons per second, on the average, arrive at a target irradiated by this beam? (Assume the beam to have uniform cross-section which is less than the target area), and (c) How fast does a hydrogen atom have to travel in order to have the same momentum as that of the photon?
12.5 — A Hydrogen Atom Initially In The Ground Level Absorbs A Photon,
Physics Class 12 · Chapter 12
12.5 A hydrogen atom initially in the ground level absorbs a photon, which excites it to the n = 4 level. Determine the wavelength and frequency of photon.
11.9 — Light Of Wavelength 488 Nm Is Produced By An Argon Laser Which Is
Physics Class 12 · Chapter 11
11.9 Light of wavelength 488 nm is produced by an argon laser which is used in the photoelectric effect. When light from this spectral line is incident on the emitter, the stopping (cut-off) potential of photoelectrons is 0.38 V. Find the work function of the material from which the emitter is made.
📋 Question Details
- Chapter
- Dual Nature of Matter
- Topic
- Photon Energy
- Year
- 2019
- Shift
- 10 Apr Shift 2
- Q Number
- Q27
- Type
- MCQ
- NCERT Ref
- Class 12 Physics Ch 11: Dual Nature of Matter
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