## Calculating amount of photons

$c=\lambda v$

Phoebe Chen 4I
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### Calculating amount of photons

Does anyone know how to calculate the second part of the question? How many photons of infrared radiation does the lamp generate in 1.0s? Is there a mathematical equation?
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Ashley Zhu 1A
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Joined: Fri Sep 28, 2018 12:16 am

### Re: Calculating amount of photons

After finding the energy of a photon using the equation, E = hf (f = frequency), you just need to divide the total energy emitted (11J) by the energy per photon to get the number of photons: 11J/(1.074 x 10^-19 J).

505194972 3k
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### Re: Calculating amount of photons

Ashley Zhu 1E wrote:After finding the energy of a photon using the equation, E = hf (f = frequency), you just need to divide the total energy emitted (11J) by the energy per photon to get the number of photons: 11J/(1.074 x 10^-19 J).

How did you find that value for energy per photon?

Ashley Zhu 1A
Posts: 69
Joined: Fri Sep 28, 2018 12:16 am

### Re: Calculating amount of photons

The energy per photon can be found using the equation E = hv where h is Planck's constant and v is the frequency, which you can find from the given wavelength with the [speed of light = wavelength x frequency] equation.

Chem_Mod
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### Re: Calculating amount of photons

You can use the following equation to find the amount of energy per photon:
$\Delta E=\frac{h*c}{\lambda}$
Plug in the values, but you would need to convert 1850nm to m.
$1850nm*\frac{10^{-9}m}{1nm} = 1.850*10^{-6}m$
Planck's constant can be substituted for h
$\Delta E=\frac{(6.63*10^{-34}J*s)(3.00*10^{8}m/s)}{1.850*10^{-6}m}$
With units cancelled, E would then equal $1.074*10^{-19}J$ per photon. Because you know the total amount of Joules emitted (11J), you could then divide 11J/1.074*10^-19 J to find the total number of photons.