1. Survey of the Universe Tom Burbine tburbine@mtholyoke.edu
8/6/2018
Survey of the Universe Tom Burbine

2. Prospective Astronomy Majors Lunch
Monday, March 4th 12:15-1:10pm Kendade 303
Meet the faculty, learn about the Mars Rover, and enjoy a delicious lunch.

3. HW# 3
Due March 6

4. Characteristics of waves
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velocity = wavelength x frequency
Wavelength = distance
Frequency = cycles per second = hertz 4

5. For light c = wavelength x frequency
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For light
c = wavelength x frequency
In a vacuum, speed of light stays the same
So if wavelength goes up
Frequency does down
f = frequency
λ = wavelength
c = λ x f 5

6. Calculations c = λ x f So if the wavelength is 1 x 10-12 m
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Calculations
c = λ x f
So if the wavelength is 1 x m
3 x 108 m/s = 1 x m * f
f = 3 x 108 m/s/1 x m
f = 3 x 1020 s-1 = 3 x 1020 Hz 6

7. Calculations c = λ x f So if the frequency is 1 x 1015 Hz
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Calculations
c = λ x f
So if the frequency is 1 x 1015 Hz
3 x 108 m/s = λ * 1 x 1015 Hz
λ = 3 x 108 m/s/1 x 1015 Hz
λ = 3 x 10-7 m 7

8. Energy of light Energy is directly proportional to the frequency
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Energy of light
Energy is directly proportional to the frequency
E = h * f
h = Planck’s constant = x J*s
since f = c/λ
Energy is inversely proportional to the wavelength
E = hc/λ 8

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Calculations
What is the energy of a radio wave with a frequency of 1 x 107 Hz?
E = h * f
h = Planck’s constant = x J*s
E = x J*s * 1 x 107
E = x J 9

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Calculations
What is the energy of a gamma ray photon with wavelength of 1 x m
E = hc/λ
h = Planck’s constant = x J*s
E = x J*s * 3 x 108 m/s / 1 x m
E = 1.99 x J 10

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12. Higher the frequency, Higher the energy of the photon
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VIBGYOR
violet
red
Higher the frequency, Higher the energy of the photon
Higher the wavelength, Lower the energy of the photon 12

13. ROYGBIV ROYGBIV Red – long wavelength Violet – short wavelength
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ROYGBIV
ROYGBIV
Red – long wavelength
Violet – short wavelength

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15. Any Questions?