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PHYSICS 002 Midterm 1
Date: 11 March 2004
Time allowed: 70 minutes
Total: 70 marks
Name:
Student ID:
Seat:
A
Useful data:
Section
Marks
A
Velocity of light = 300,000 km/s
B
1 AU = 1.5 108 km
C1
Solar radius = 6.96 105 km
C2
Total
Section A: Multiple choice (12 marks)
(1) If the local time is 9 pm, and the Moon is rising from the East, the most likely phase of the Moon is:
A.
new
B.
crescent
C.
quarter
D.
gibbous
E.
full Answer:____
(2) If you heat a gas so that collisions continuously excite electrons to higher energy levels, then when the electrons fall back to lower energy levels the gas produces
A. black body radiation.
B. scattered electromagnetic radiation.
C. diffracted electromagnetic radiation.
D. an absorption line spectrum.
E. an emission line spectrum. Answer:____
(3) Which of the following statements about thermal radiation is always true?
A. A hot object emits more radio waves than a cool object.
B. A hot object emits less total radiation than a cool object.
C. A hot object emits more total radiation than a cool object.
D. A hot object emits more X rays than a cool object.
E. A hot object emits more total radiation per unit surface area than a cool object.
Answer:____
Section B: True or False (22 marks)
(1-3) Determine whether the following statements about stellar spectra are true or false.
True
False
(1) A B5 star is cooler than a star whose peak of radiation is located at 600 nm.
(2) A star which has a very broad ionized calcium absorption line is moving away from the Sun.
(3) A K5 star is less luminous than a star of temperature
7,000 K and of the same radius.
(4-5) Compare the following two Earthbound astronomical telescopes: (a) a century-old refracting telescope with an objective lens of diameter 2 m; (b) a modern reflecting telescope with a diameter of 4 m. Determine whether the following statements are true or false.
True
False
(4) The old telescope has less light gathering power than the modern one.
(5) The old telescope has less resolving power than the modern one.
(6-8) The wavelength of an H Balmer absorption line is 656.3 nm. The observed wavelength of the line from an A0 star is found to be 657.0 nm. Determine whether or not the 3 cases described in Fig. 1 are possible for the movement of the star?
Figure 1: Movement of a star with an H Balmer absorption line
True
False
(6) Fig. 1(a) corresponds to a possible movement of the star.
(7) Fig. 1(b) corresponds to a possible movement of the star.
(8) Fig. 1(c) corresponds to a possible movement of the star.