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## The energy efficiency of an incandescent light bulb (= the percentage of consumed power that is actually converted into radiated light) is t

Question

The energy efficiency of an incandescent light bulb (= the percentage of consumed power that is actually converted into radiated light) is typically around 5%. Suppose a certain brand of 75 W incandescent bulb emits light primarily at wavelength ???? = 570 nm.

Calculate the total number of photons emitted by one of those bulbs if it has been shining for a 6-hour period.

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Physics
3 years
2021-07-28T00:40:42+00:00
2021-07-28T00:40:42+00:00 1 Answers
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## Answers ( )

Answer:4*10^22 photons

Explanation:To find the number of photons is necessary to calculate the total energy of the light emitted in one hour = 3600s:

Furthermore, is necessary to find the associated energy to the photon 0f 570nm with following formula:

h: Planck’s constant = 6.62*10^-34 Js

c: speed of light = 3*10^8 m/s

wavelength = 570*10^-9 m

Finally you divide E’ between Ep to find the number of photons:

the number of emitted photons is 4*10^22