Green light has a wavelength of 5200 A. How do you calculate the energy of one photon of green light?

1 Answer
Aug 15, 2017

E = 3.8xx10^-19 "J"

Explanation:

We're asked to calculate the energy of one photon of a green light, given its wavelength of 5200 "Å".

To do this, we can use the equation

ul(E = (hc)/f

where

  • E is the energy of the photon (in joules)

  • h is Planck's constant, equal to 6.626xx10^-34 "J"•"s"

  • c is the speed of light in vacuum, 299792458 "m/s"

  • f is the frequency of the photon (in meters)

We need to convert from ångströms to meters, using the conversion factor

1 "m" = 10^10 "Å":

5200cancel("Å")((1color(white)(l)"m")/(10^10cancel("Å"))) = color(red)(ul(5.2xx10^-7color(white)(l)"m"

The energy of the photon is thus

color(blue)(E) = ((6.626xx10^-34color(white)(l)"J"•cancel("s"))(299792458cancel("m/s")))/(color(red)(5.2xx10^-7cancel("m"))) = color(blue)(ulbar(|stackrel(" ")(" "3.8xx10^-19color(white)(l)"J"" ")|)

rounded to 2 significant figures.