Deck 6: Light and Telescopes

Question 1

Which of the following is true about the frequency and wavelength of electromagnetic waves?

A)The product of frequency and wavelength is the same for all such waves
B)As frequency increases,wavelength increases
C)Frequency is constant for all wavelengths
D)Frequency and wavelength are independent of each other

Answer 1

The product of frequency and wavelength is the same for all such waves

Question 2

How many 4 meter telescopes would be required to match the light-gathering power of a 15 meter telescope?

A)2
B)6
C)14
D)20

Answer 2

14

Question 3

Which of the following kinds of photons are least energetic?

A)Infrared
B)Visible
C)Ultraviolet
D)X-ray

Answer 3

Infrared

Question 4

The product of the wavelength and frequency of a wave is equal to

A)The speed of the wave
B)The energy of the wave
C)The distance between crests of the wave
D)The temperature of the wave

Question 5

A TV satellite broadcasts at a frequency of 5000 MHz,(1 MHz = 1 million Hertz).What is the wavelength of this radiation?

A)1000 cm
B)5 million centimeters
C)6 cm
D)0.3 cm

Question 6

Compared with infrared waves,radio waves

A)Have higher energy
B)Have lower frequency
C)Take much longer to reach us from celestial objects
D)Have shorter wavelengths

Question 7

A particle of light is a

A)Graviton
B)Proton
C)Spectrum
D)Photon
E)Angstrom

Question 8

Which of the following forms of electromagnetic radiation has the longest wavelength?

A)Visible
B)X-ray
C)Infrared
D)Ultraviolet

Question 9

Suppose you want to determine if there is any methane gas on a newly discovered planet.You need to equip your telescope with a

A)CCD
B)Photographic plate holder
C)Spectrometer
D)Space probe,since you can't determine anything about gases without travelling there.

Question 10

The same telescope is used to obtain an image using light of the following wavelengths.Which of the images will have the poorest angular resolution?

A)Blue
B)Yellow
C)Red
D)Infrared

Question 11

When used at a wavelength of 1 micron,a telescope can resolve angles as small as 0.1 seconds of arc.How small an angle could the telescope resolve when used at a wavelength of 5 microns?

A)0.02 seconds of arc
B)0.004 seconds of arc
C)0.5 seconds of arc
D)0.25 seconds of arc

Question 12

How does the speed of light in glass compare to the speed of light in a vacuum?

A)It is larger in glass
B)It is larger in a vacuum
C)Trick question,light can't travel in glass
D)They are the same

Question 13

The wavelength of a wave is 2 meters.The frequency of the wave is 2 Hz.What is the speed of the wave?

A)16 m/s
B)4 m/s
C)64 m/s
D)0.25 m/s

Question 14

Which of the following are NOT electromagnetic waves?

A)Radio waves
B)Optical light
C)X-rays
D)Gravitational waves

Question 15

The focal ratio of a lens or mirror is the ratio of its

A)Focal length to diameter
B)Diameter to thickness
C)Magnification to diameter
D)Focal length to thickness

Question 16

How does the light-gathering power of a 40 cm telescope compare to that of a 20 cm telescope?

A)They are the same
B)2 times as great
C)4 times as great
D)8 times as great

Question 17

Telescope A has a mirror that is 10 times larger than the mirror of telescope B.Telescope A can resolve an angle as small as 0.1 seconds of arc.
What is the smallest angle that can be resolved by telescope B?

A)10 seconds of arc
B)1 second of arc
C)0.1 second of arc
D)0.01 second of arc

Question 18

Radio astronomers obtain great angular resolution by

A)Observing at the longest wavelength possible
B)Using arrays of radio telescopes
C)Observing objects when they are near the horizon
D)Observing an object with the same telescope for many years

Question 19

A telescope that uses a lens to bring radiation to a focus is called a

A)Radio telescope
B)Reflector
C)Refractor
D)Photometer

Question 20

Which of the following forms of electromagnetic waves (or photons)has the greatest energy?

A)Visible
B)X-ray
C)Infrared
D)Ultraviolet

Question 21

In the laboratory,an atom emits a spectral line at a wavelength of 400 nanometers.In the spectrum of a star,the same spectral line is found to have a wavelength of 410 nanometers.What can be said about the star?

A)It is hotter than the Sun
B)It is moving toward the Earth
C)It is moving away from the Earth
D)It contains elements that are not found on Earth

Question 22

Why do X-ray telescopes have to be placed in space satellites?

A)They are too sensitive to terrestrial radiation
B)They are too dangerous for astronomers to operate on the ground
C)The Earth's atmosphere absorbs cosmic X-rays
D)There is too much scattered sunlight in the Earth's atmosphere
E)The mirrors for X-ray telescopes are too large to operate on the ground

Question 23

The Doppler Effect is _____________________.

A)the speed of light divided by the frequency of the wave
B)the change in the wavelength divided by the change in the frequency
C)the change in frequency and wavelength of a wave due to motion between the source and observer
D)the decrease in wave intensity with increasing distance from the source

Question 24

Adaptive optics are used to produce what effect?

A)Optical compensation for atmospheric turbulence
B)Automatic changing of the magnification
C)Produce increases in the appeture diameter
D)Combine telescopic arrays to increase resolution of the image

Question 25

In the laboratory,a spectral line of an element has a wavelength of 5000 Angstroms.What would be the measured wavelength of that line in the spectrum of a planet that is approaching at a velocity of 30 km/s? (The speed of light is 300,000 km/s. )

A)4999.5 Angstroms
B)4995 Angstroms
C)5000.5 Angstroms
D)5005 Angstroms

Question 26

A star is moving away from an observer at 1% of the speed of light.At what wavelength would the observer find an emission line that would occur at a wavelength of 6000 Angstroms if the star were at rest?

A)6060 Angstroms
B)6010 Angstroms
C)6000 Angstroms
D)5940 Angstroms

Question 27

The magnification in a refracting telescope is calculated in what way?

A)Compute the ratio of the focal length of the eyepiece lens to the focal length of the objective lens
B)Compute the ratio of the focal length of the objective lens to the focal length of the eyepiece lens
C)Multiply 1.22 by the diameter of the appeture lens
D)Compute the square of the length of the telescope

Question 28

Which of the following is not likely to be an attribute of a good observing site?

A)Dark sky
B)Atmospheric stability
C)Low elevation
D)Low humidity