Name ________________________
C= λv
E = hv
E is the energy of the light in Joules (J),
h is a constant which is 6.626 X 10-34 J·s, and
v is the frequency of the light in s-1 or waves/s (also called Hertz (Hz).
C is the speed of light. C = 3.00 X 108 meters/sec.
λ is the wavelength
(There are 1 X109 nanometers in one meter.)
Use the formulas above and the table below to answer the questions which follow.
Frequency,
s-1 or (1/s)
Color
7.1 X 1014
6.4 X 1014 5.7 X 1014
5.2 X 1014
4.8 X 1014
4.3 X 1014
violet
blue
yellow
orange
red
green
1. A photon of light with an energy of 2.2 X 10-19 Joules is emitted. What is the
frequency of this photon?
What color is it?
2. What is the wavelength, in nanometers, of light with a frequency of 7.1 X 1014 Hz?
3. A photon of light has a wavelength of 698 nm. How much energy does it have in
Joules?
What color is it?
4. How much energy does a photon of light carry if it has a wavelength of 526
nanometers?
What color is that photon?
5. What is the wavelength, in nanometers, of a photon of light if it has an energy of
4.01 X 10-19 Joules?
What color is it?
6. What is the wavelength, in nanometers, of a photon of light with an energy of 1.66 X
10-19 Joules?
What color is it?
Answers:
1. 3.3 X 1014 Hz, infrared
2. 420 nm, violet
3. 2.85 X 10-19 J, red
4. 3.78 X 10-19 J, green
5. 496 nm blue/green
6. 1.20 X 103 nm, infrared