Name ______

E = hv C= λv

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, s1 or (1/s) / 7.1 X 1014 / 6.4 X 1014 / 5.7 X 1014 / 5.2 X 1014 / 4.8 X 1014 / 4.3 X 1014
Color / violet / blue / green / yellow / orange / red

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