NAME Si vi Bosinyan an Physics 103 Spring 2016 Final Exam For the final exam, yo

Question

NAME Si vi Bosinyan an Physics 103 Spring 2016 Final Exam For the final exam, you may use your handy information sheet, and two sheets of notes with whatever you want to put on it, front and back. Please sit every other seat, and please don't cheat! If something isn't clear, please ask. You may use calculators. All problems are weighted equally. PLEASE BOX YOUR FINAL ANSWERS! You have the full length of the class. If you attach any additional length of the class. If you attach any additional scratch work, then make sure that your name is on every sheet of your work. Good luck 1. The Lyman series for the elec- tron transition between states in an atom in a distant galaxy is observed Transition I Observed (nm) | Hydrogen (nm) by astronomers. The wavelnths2-1 Lyman Series Observations of the first four lines and the short- wavelength (ionization) limit of this series are given in the table to the right, along withthecorresponding 202.6 170.9 162.1 158.3 152.0 121.6 102.6 97.3 95.0 51 001 91.2 transition wavelengths for hydrogen observed in the lab. (a) Show that the wavelengths of the first four lines and the short wavelength limit of the Lyman series for the hydrogen atom are all 60% of the observed Lyman series for the extragalactic atom. (b) Determine the recession velocity of the galaxy in km/s. (e) Using Hubble's law, u = Hod, where Ho = 68 km/s/Mpc is the Hubble constant (one megaparsec, Mpc, is 3.26 million light years), determine the distance to the galaxy in light years.

Explanation / Answer

Problem 1)

part a)

We use a rule of direct proportions

202.6 nm ----- 100%

121.6 nm ---- x

x = 121.6 100/ 202.6

x = 60%

170.9 nm ---- 100%

102.6 nm ---- x

x = 102.6/170.9 100

x = 60%

162.1 nm ----- 100%

97.3 nm ---- x

x = 97.3/162.1 100

x = 60 %

158.3 nm – 100%

95.0 nm — x

x = 95/158.3 100

x = 60%

152.0 nm ---- 100%

91.2 nm ---- x

x = 91.2/152 100

x = 60%

Part b)

the expression for the doppler effect is

fo = fs sqrt (( 1+)/(1-))

= v/c

c= fo o

c= fs s

c/ o = c/ s sqrt (( 1+)/(1-))

s /o = sqrt (( 1+)/(1-))

form part a

0.602= ( 1+)/(1-)

0.36 (1-v/c) = 1 + v/c

v/c + 0.36 v/c = 1 – 0.36

1.36 v/c = 0.64

v = 0.64c/1.36

v = 0.47 c

v = 0.47 3 108 m/s

v = 1.41 108 m/s

v = 1.41 105 km/s

Part c)

d = v / Ho

d = 1.41 105/68

d = 2.07 103 Mpc

Related Questions

Navigate

• Browse (All)
• Browse N
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.