Name: ________________________


                                        Student Number: ______________

Source 1 because it emits most of its light at a shorter wavelength, hence more energetic, bluer light. You do not need to know exactly what the units "nm" are since both stars use the same units. However, a "nm" = nanometer which is 1 billionth of a meter.

2. (5 pts) You observe two stars on a clear night, one of which appears bluish and the other reddish. What can you conclude about these stars' surface temperatures?

The red star's surface is cooler than the blue star's surface.

3. (3 pts) Arrange the following types of light in order of INCREASING ENERGY: x-rays, infrared, yellow, green, microwaves

(a) infrared (lowest), x-rays, yellow, green, microwaves (highest)
(b) microwaves (lowest), infrared, yellow, green, x-rays (highest)
(c) yellow (lowest), green, microwaves, infrared, x-rays (highest)
(d) x-rays (lowest), microwaves, green, yellow, infrared (highest)
(e) x-rays (lowest), green, yellow, infrared, microwaves (highest)

4. (5 pts) Below is a sketch of a wave. Superimpose on it a sketch of another wave with the same amplitude but a wavelength twice as long.

A correct drawing has the same amplitude, but half as many peaks and valleys (2 rather than 4).

5. (5 pts) One advantage of using a detector other than the human eye with a telescope is

Samples of some correct answers:
The detector is more sensitive, i.e., it sees fainter objects, or
The detector's output can be digitized, i.e., transferred easily onto a computer, or
The detector can take spectra, or
The detector can see more wavelengths than just optical (visual) light.

6. (3 pts) Particles (atoms, ions, nuclei, electrons, molecules) move faster when they are

(a) farther apart
(b) closer together
(c) cooler
(d) hotter
(e) none of these

7. (3 pts) When an electron emits a photon, the electron

(a) gains energy
(b) loses energy
(c) keeps the same energy
(d) joins the nucleus
(e) leaves an atom

8. (5 pts) The Galilean moons of Jupiter and Jupiter have about the same surface temperature. Jupiter appears bright, but we need a telescope or binoculars to see the fainter Galilean moons. Why do the moons appear fainter?

The Galilean Moons are smaller in size than Jupiter. Hence there are fewer atoms on their surface reflecting light from the Sun and they are fainter.

9. (3 pts) When you see a star, light

(a)is emitted by the star and enters your eye
(b)is reflected by the star and enters your eye
(c)is emitted by your eye and reflected from the star
(d)goes from the sun to the star and then back to your eye
(e)goes from the sun to your eye and then to the star