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Monochromatic light of wavelength 667 nm is produced by a helium neon laser. The power emitted is 9 mW. The number of photons arriving per second on the average at a large irradiated by this beam is:
Options
(a) 3 x 10¹⁶
(b) 9 x 10¹⁵
(c) 3 x 10¹⁹
(d) 9 x 10¹⁷
Correct Answer:
3 x 10¹⁶
Explanation:
λ = 667 x 10⁻⁹ m, P = 9 x 10⁻³ W
P = Nhc / λ, N = no. of photons emitted/sec.
N = (9 x 10⁻³ x 667 x 10⁻⁹) / (6.6 x 10⁻³⁴ x 3 x 10⁸)
= 9 x 6.67 x 10⁻¹⁰ / 3 x 6.6 x 10⁻²⁶
3 x 10¹⁶ / sec
Related Questions: - A body moves with a uniform acceleration a and zero initial velocity
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Topics: Dual Nature of Matter and Radiation
(150)
Subject: Physics
(2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
- A body moves with a uniform acceleration a and zero initial velocity
- A proton is moving in a uniform magnetic field B in a circular path of radius a
- A point source emits sound equally in all directions in a non-absorbing medium.
- A light whose frequency is equal to 6.0 x 10¹⁴ Hz is incident on a metal
- 10 mA current can pass through a galvanometer of resistance 25 ohm.
Topics: Dual Nature of Matter and Radiation (150)
Subject: Physics (2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
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