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### Atomic Spectra Post-Assessment Q. 29

Posted: Sun Oct 08, 2017 6:34 pm
In 1.0 s, a 60 W bulb emits 11 J of energy in the form of infrared radiation (heat) of wavelength 1850 nm. What is the energy per photon of light emitted? How many photons of infrared radiation does the lamp generate in 1.0 s?

I understand how to find the energy per photon (1.074 x 10-19 J), but how do you calculate the number of photons that are generated in 1 second?

Also, is 60 W and 11 J emitted just extra information?

### Re: Atomic Spectra Post-Assessment Q. 29  [ENDORSED]

Posted: Mon Oct 09, 2017 1:11 am
The bulb emits 11 J of energy in the form of infrared radiation. Since you know that the energy per photon of light emitted is $\1.074*10^{-19} J/photon$, you can use dimensional analysis to find the number of photons in 1 second (in 1 second, the bulb emits a total of 11 J of energy): $\frac{11 J}{1.074* 10^-19 J/photon} = 1.0*10^{20} photons.$

### Re: Atomic Spectra Post-Assessment Q. 29

Posted: Fri Oct 13, 2017 7:57 pm
Hi, so how do you calculate the energy per photon? I tried calculating the energy per photon but I got a different answer.