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Chapter 38: Q13. (page 1114)

A 100 W incandescent lightbulb emits about 5 W of visible light. (The other 95 W are emitted as infrared radiation or lost as heat to the surroundings.) The average wavelength of the visible light is about 600 nm, so make the simplifying assumption that all the light has this wavelength. How many visible-light photons does the bulb emit per second?

Short Answer

Expert verified

1.5092×1019photons/sec

Step by step solution

01

Given Parameters.

Energy Emitted by bulb in form of visible light: 5W

Wavelength of Light: 600nm

02

Formula Used:

Energy of single photon = hcλ

Energy emitted by bulb in form of light per second : 5W = 5J/s

No. of photons emitted per second: EnergyemittedbybulbpersecondEnergyofphoton

5hcλ=5λhc=5J/s×600×10-9m6.626×10-34Js×3×108m/s=1.5092×1019photons/s

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