Green light has a wavelength of 5200 A. How do you calculate the energy of one photon of green light?
1 Answer
Explanation:
We're asked to calculate the energy of one photon of a green light, given its wavelength of
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.