Astronomy 100 Tuesday, Thursday 2:30 - 3:45 pm Tom Burbine [email protected]
Survey of the Universe Tom Burbine tburbine@mtholyoke
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Transcript of Survey of the Universe Tom Burbine tburbine@mtholyoke
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Prospective Astronomy Majors Lunch
Meet the faculty, learn about the Mars Rover, and enjoy a delicious lunch.
Monday, March 4th
12:15-1:10pmKendade 303
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HW# 3
• Due March 6
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Characteristics of waves• velocity = wavelength x frequency• Wavelength = distance• Frequency = cycles per second = hertz
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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
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Calculations
• c = λ x f• So if the wavelength is 1 x 10-12 m• 3 x 108 m/s = 1 x 10-12 m * f• f = 3 x 108 m/s/1 x 10-12 m • f = 3 x 1020 s-1 = 3 x 1020 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
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Energy of light
• Energy is directly proportional to the frequency• E = h * f• h = Planck’s constant = 6.626 x 10-34 J*s• since f = c/λ• Energy is inversely proportional to the wavelength• E = hc/λ
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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 = 6.626 x 10-34 J*s• E = 6.626 x 10-34 J*s * 1 x 107
• E = 6.626 x 10-27 J
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Calculations
• What is the energy of a gamma ray photon with wavelength of 1 x 10-15 m
• E = hc/λ• h = Planck’s constant = 6.626 x 10-34 J*s• E = 6.626 x 10-34 J*s * 3 x 108 m/s / 1 x 10-15 m• E = 1.99 x 10-10 J
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Higher the frequency, Higher the energy of the photonHigher the wavelength, Lower the energy of the photon
redviolet
VIBGYOR
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ROYGBIV
• ROYGBIV • Red – long wavelength• Violet – short wavelength
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http://www.arpansa.gov.au/images/basics/emr.jpg
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Any Questions?