HON 203 Lab 2
EM Spectrum - A Calculation Investigation
You are given the following two equations that express the relationships between the speed, the
wavelength, the energy and the frequency of light:
c=ln
speed = wavelength x frequency
E = hn
energy = Planck's constant x frequency
1. Check the equations above and show that the units match on each side of the equations.
2. Manipulate both equations to solve for energy (E) as a function of wavelength (l) and fundamental
constants. Show each step. Show that the units match on each side of the resulting equations.
3. Given a photon's wavelength, frequency or energy in the chart below, use the above equations to
solve for the other two (in the units indicated). Use the useful constants page if you need to.
4. Summarize what you have learned about light and the relationship between its energy, frequency
and wavelength.
Wavelength (m)
Frequency (Hz)
Energy (J)
0.001
7.0 x 1013
5.0 x 10-7
2.0 x 10-15
1.2 x 1022
Electromagnetic
Radiation Range
Useful Constants



speed of light (c) = 3.0 x 108 m/s
Planck's Constant (h) = 6.626 x 10-34 Joules second
Charge of an electron (q) = 1.602 x 10-19 coulombs
Useful Units



frequency = cycles/second (Hz)
wavelength = length (m)
volt = a unit of potential of electric field, such that that it takes 1 Joule to push a charge of 1
Coulomb across 1 volt
Conversion Factors


1 angstrom (A) = 1 x 10-10 meters (often used for the optical region of the spectrum)
1 KeV = 1,000 eV = 1.6 x 10-16 Joules