### Atomic Spectrum Module #28

Posted: **Fri Oct 19, 2018 6:43 pm**

by **melodyzaki2E**

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?

Can someone please explain how to solve this question please? thanks.

### Re: Atomic Spectrum Module #28

Posted: **Fri Oct 19, 2018 9:07 pm**

by **Samantha Pacheco 2K**

First you are going to convert the wave length from nm to meter. 1850nm= 1.85x10^-6 m. In order to find the # of photons first calculate the energy of each photon using E =hc/λ.

=(6.626 × 10−34 J · s)(3 × 108 m/s) /1.85 × 10−6 m

= 1.07449 × 10−19 J (per photon)

Now that you have the energy of one photon you are going to divide your total energy (11 J) by energy of each photon ( 1.07449 × 10−19 J)

# of photons= 11J/1.07449 × 10−19 J

= 1.02374 × 1020 photons