EXPLANATION 
Light has wave characteristics;
wavelength is the
peak to peak distance
of two adjacent waves.

030102 
"Wavelength" 
( symbol is λ )
is equal to the "Velocity of light" divided by the frequency.
( λ = 3 * 10^{8}/ f )
The wavelength of Light is so small that it is conveniently expressed in
nanometres ( nm )
which are equal to onebillionth of a meter. Wavelength as the distance,
measured in the direction of propagation of a wave, between two successive
points in the wave that are characterized by the same phase of
oscillation. 
"nm" (
nanometre ) 
A unit of measure often used when discussing wavelengths of Light.
µm (micrometer) is also used sometimes. 
"Frequency" 
( symbol is f ) is equal to the "Velocity of light"
divided by the wavelength. ( f = 3 * 10^{8}/λ ) 
"Velocity
of light" 
( symbol is c ) is approximately 300,000
kilometres per second
( about 186,000 miles per second )
( c = f * λ ) ( c as m/s ) ( f as "Hz"
) and ( λ as m ) 
"Hz" 
Frequency is expressed in Hertz ( "Hz"
); a frequency of 1 Hz means that there is 1 cycle or oscillation per second. 
030103 
Hertz, Heinrich,
Rudolf
(German physicist)
b18570222
Hamburg Germany
d18940101
Bonn
Germany 
"Energy" 
The light has specific frequencies associated with the energy quanta. To remove an electron from
an atom requires several electron volts, depending on the atom. There are 2.26 x 10^{25 }eV in one kilowatthour.
Visible light has a quantum energy of approximately 2 eV. 
"eV" 
Energy at the atomic level is commonly expressed in electron volts ( eV ) 
Length Conversion 
1 nm = 10^{9} m = 10^{6} mm = 10^{3} µm
1 µm = 10^{6} m = 10^{3} mm = 1000 nm
