Question

Neon discharge tubes emit a light with a wavelength of 600. Nm that appears deep orange to the human eye. How many photons of this electromagnetic radiation amount to 250. J of energy?

Answer 1

`7.53\cdot 10^(20)`

Step-by-step explanation:

First of all, we need to calculate the energy of one photon with wavelength 600 nm. The energy of each photon is given by

`E=(hc)/(\lambda)`

where

`h=6.63\cdot 10^(-34) Js` is the Planck's constant

`c=3\cdot 10^8 m/s` is the speed of light

`\lambda=600 nm=6\cdot 10^(-7) m` is the wavelength of the light

Substituting numbers into the formula, we find

`E_1=((6.63\cdot 10^(-34)Js)(3\cdot 10^8 m/s))/(6\cdot 10^(-7) m)=3.32\cdot 10^(-19) J`

Now to find the number of photons, we simply divide the total energy (250 J) by the energy of one photon:

`n=(E)/(E_1)=(250 J)/(3.32\cdot 10^(-19) J)=7.53\cdot 10^(20)`