| ⇦ | 
| ⇨ |
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: - A stone falls freely under gravity.It covers distances h₁,h₂ and h₃
- Three unequal resistors in parallel are equivalent to a resistance 1 Ω.
- A mass of 2.0 kg is put on a flat plan attached to a vertical spring fixed on the ground
- A hollow sphere of charge does not produce an electric field at any
- Equal currents are passing through two very long and straight parallel wires
Topics: Dual Nature of Matter and Radiation
(150)
Subject: Physics
(2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
- A stone falls freely under gravity.It covers distances h₁,h₂ and h₃
- Three unequal resistors in parallel are equivalent to a resistance 1 Ω.
- A mass of 2.0 kg is put on a flat plan attached to a vertical spring fixed on the ground
- A hollow sphere of charge does not produce an electric field at any
- Equal currents are passing through two very long and straight parallel wires
Topics: Dual Nature of Matter and Radiation (150)
Subject: Physics (2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
18000+ students are using NEETLab to improve their score. What about you?
Solve Previous Year MCQs, Mock Tests, Topicwise Practice Tests, Identify Weak Topics, Formula Flash cards and much more is available in NEETLab Android App to improve your NEET score.
Share this page with your friends
Leave a Reply