Phys 100 – Astronomy Review Questions

The ___________ of a telescope is a measure of its ability to show fine detail and depends on the diameter of the objective.

• a. light-gathering power

• b. focal length

• c. magnifying power

• d. resolving power

Observations of radio waves from astronomical objects suffer from poorer resolution than visible observations because

• a. the signals are so weak in the radio region.

• b. the wavelength of radio waves is much longer than the wavelengths of visible light.

• c. radio telescopes are generally much smaller in diameter than optical telescopes.

• d. it is very difficult to detect radio waves

Radio telescopes are _______ telescopes.

• a. Reflecting

• b. Refracting

• c. Deflecting

• d. Compound

A telescope whose objective is a lens and contains no mirrors is a(n) _____ telescope.

• a. Refracting

• b. Reflecting

• c. Deflecting

• d. Compound

Which of the following telescopes has the larger light-gathering power?

• a. A telescope of 5 cm diameter and focal length of 50 cm.

• b. A telescope of 6 cm diameter and focal length of 100 cm.

• c. A telescope of 2 cm diameter and focal length of 100 cm.

• d. A telescope of 3 cm diameter and focal length of 75 cm.

The resolving power of a telescope is _____.

• a. measure of the minimum angular separation that can be seen with the telescope.

• b. a measure of the maximum angular separation that can be seen with the telescope.

• c. a measure of the amount of light that the telescope can gather in one second.

• d. the separation between the objective and the image.

• e. a measure of how blurry object appear in the telescope

What is the wavelength of the longest wavelength light visible to the human eye?

• 400 nm

• 4000 nm

• 7000 nm

• 700 nm

• 310^8 m

Violet light has a wavelength of approximately ____________.

• 400 nm

• 4000 nm

• 7000 nm

• 700 nm

• 310^8 m

Chromatic aberration occurs in a __________telescope when

• reflecting; different colors of light do not focus at the same point.

• refracting; different colors of light do not focus at the same point.

• reflecting; light of different wavelengths get absorbed by the mirror.

• refracting; light of different wavelengths get absorbed by the lens.

The main reason for positioning many radio telescopes across a large area and combining the signals is

• to observe more objects in a shorter amount of time.

• provide a backup system if one or more of the telescopes go down.

• to produce higher resolution images.

• to avoid interference between signals from the separate telescopes.

• to account for the motion of objects in the sky as a result of the Earth’s rotation.