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A 200 W sodium street lamp emits yellow light of wavelength 0.6 µm. Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is
Options
(a) 1.5 x 10²⁰
(b) 6 x 10¹⁸
(c) 62 x 10²⁰
(d) 3 x 10¹⁹
Correct Answer:
1.5 x 10²⁰
Explanation:
Give that, only 25% ov 200 W converter electrical energy into light of yellow colour
(hc / λ) x N = 200 x 25/100
Where N is the no. of photons emitted per second, h = plank’s constant, c, speed of light
N = 200 x 25 / 100 x λ / hc
= 200 x 25 x 0.6 x 10⁻⁶ / (100 x 6.2 x 10⁻³⁴ x 3 x 10⁸)
= 1.5 x 10²⁰
Related Questions: - We get Balmer series when electron comes from
- Light of wavelength 500 nm is incident on a metal with work function 2.28 eV.
- A uniform electric field and uniform magnetic field are acting along the same
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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
- We get Balmer series when electron comes from
- Light of wavelength 500 nm is incident on a metal with work function 2.28 eV.
- A uniform electric field and uniform magnetic field are acting along the same
- A particle moves in a circle of radius 5 cm with constant speed and time period
- Work done by an external agent in separating the parallel plate capacitor is
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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