Survey of the Universe Tom Burbine tburbine@mtholyoke

1. Survey of the UniverseTom Burbinetburbine@mtholyoke.edu

2. Prospective Astronomy Majors Lunch Monday, March 4th12:15-1:10pmKendade 303 Meet the faculty, learn about the Mars Rover, and enjoy a delicious lunch.

3. HW# 3 • Due March 6

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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

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

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

14. http://www.arpansa.gov.au/images/basics/emr.jpg

15. Any Questions?