Equations
  
Density

    

  • D = m/V


  • V = m/D


  • m = V•D


Speed

distance/time

e.g. m/s or mi/hr
    


  • Speed of light
c = 2.998 • 108 m/s


  • Planck's constant
h = 6.626 • 10-34 J•s


  • Wavelength of light (lambda)
λ is in meters


  • Frequency of light (nu)
ν is in reciprocal seconds, 1/s, or Hz (same thing)


  • Speed of light(c)=wavelength(λ)•frequency(ν)


  • Energy of a photon of light = h • frequency (ν)


Example
A photon of light has a frequency of 5.45 • 1014 Hz.
What is its wavelength and energy? 
It is in the visible range. What color light is it?

nu(ν)=5.45•1014Hz=5.45•1014 1/s
c=3.00•108 m/s
    


  1. Use:
(3.00•108m/s)/(5.45•1014
1/s)

= 5.50 • 107 m


  2. Then, 5.50 • 107 m = 550 nanometers, which is slightly
greenish-yellow


  3. To find its energy, use Planck's equation:

=(6.626•10-34J•s)•(5.45•1014 1/s)
 
= 3.61 • 10-19 Joules