Deck 6: Light and Telescopes

Question 1

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

A) 400 nm
B) 4000 nm
C) 7000 nm
D) 700 nm
E) 3*10⁸ m

Answer 1

400 nm

Question 2

A telescope that suffers from chromatic aberration and has a low light gathering power is most likely

A) a small diameter objective reflecting telescope.
B) a small diameter objective refracting telescope.
C) a large diameter objective refracting telescope.
D) a large diameter objective reflecting telescope.
E) the Hubble Space Telescope.

Answer 2

a small diameter objective refracting telescope.

Question 3

What is the ratio of the light gathering power of a 5-m telescope to that of a 0.5-m telescope?

A) 10
B) 0.1
C) 0.01
D) 100
E) 25

Answer 3

100

Question 4

Your favorite radio station broadcasts at a frequency of 1.00*10⁸ Hz.What is the wavelength of this transmission?

A) 3*10⁸ m
B) 3*10¹⁶ m
C) 3 m
D) 0.33 m
E) 3* ^{- 8} m

Question 5

Ultraviolet radiation from a star

A) will not penetrate Earth's atmosphere and reach the ground.
B) has a wavelength that is longer than the visible light emitted by the star.
C) has a wavelength that is shorter than the x-rays emitted by the star.
D) a and b
E) b and c

Question 6

The technique called ____ uses a high-speed computer to monitor atmospheric distortion and adjust the optics of a telescope to partially compensate for the seeing.

A) photometry
B) chromatic aberration
C) active optics
D) spherical aberration
E) adaptive optics

Question 7

Astronomers build optical telescopes on tops of mountains because

A) there is less air to dim the light.
B) the seeing is better.
C) CCDs work better when there is less oxygen in the air.
D) all of the above
E) a and b

Question 8

The ____ of a telescope depends on the diameter of the objective lens or mirror.

A) light-gathering power
B) resolving power
C) magnifying power
D) both answers "a" and "b"

Question 9

A beam of light from a laser has a wavelength of 600 nm.What is the frequency of this light?

A) 5*10¹⁴ Hz
B) 6000 Hz
C) 3*10⁸ m/s
D) 2* ^{- 15} Hz
E) 1.8*0¹² Hz

Question 10

____ has (have)wavelengths that are shorter than visible light.

A) Gamma-rays
B) Ultraviolet light
C) Infrared radiation
D) Radio
E) a and b

Question 11

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

A) 400 nm
B) 4000 nm
C) 7000 nm
D) 700 nm
E) 3*10⁸ m

Question 12

There are ____ nanometers in one meter.

A) 1*10³
B) 1* ^{- 3}
C) 1*10⁹
D) 1* ^{- 9}
E) 400

Question 13

What is the magnification of a telescope and eyepiece if the telescope objective has a focal length of 200 cm and the eyepiece has a focal length of 0.2 cm?

A) 400 times
B) 4000 times
C) 100 times
D) 1000 times
E) 40 times

Question 14

Violet light has a wavelength of approximately ____.

A) 400 nm
B) 4000 nm
C) 7000 nm
D) 700 nm
E) 3*10⁸ m

Question 15

Infrared astronomy is often done from high-flying aircraft because

A) infrared telescopes only need to get above the ozone layer.
B) infrared radiation is absorbed low in Earth's atmosphere.
C) infrared photons are quite energetic.
D) infrared telescopes are not very heavy.
E) infrared sources are very bright.

Question 16

____ has (have)wavelengths that are longer than visible light.

A) Gamma-rays
B) Ultraviolet light
C) Infrared radiation
D) X-rays
E) a,b,and d above

Question 17

What is the energy of the photon whose wavelength is 400 nm?

A) 1.2*10¹² m
B) 1.3*10 ^{- 5} m
C) 2.7*10 ^{- 30} Joules
D) 5.0*10 ^{- 19} Joules
E) 7.5*10⁴ Hertz

Question 18

The ability of a telescope to reveal fine detail on a planet or other astronomical object is known as the telescope's ____.

A) light gathering power
B) focal length
C) resolving power
D) telescope detailing
E) aberration

Question 19

A wave traveling at a speed of 90 meters per second with a frequency of 60 Hz would have a wavelength of

A) 5400 meters.
B) 540 nm.
C) 1.5 meters.
D) 60 meters.
E) 90 meters.

Question 20

A new generation of telescopes is currently being built that overcomes the limitations of the older large telescopes.Some of these new telescopes

A) use segmented mirrors.
B) use mirrors that are very thin.
C) use active optics to control the shape of the mirror.
D) all of the above

Question 21

The resolving power of a telescope with a diameter of 232 cm is

A) 0.05 arc seconds.
B) 232 arc seconds.
C) 2.32 arc seconds.
D) 5 arc seconds.
E) 11.6 arc seconds.

Question 22

In modern astronomy,an interferometer

A) is the highest resolution optical telescope ever built.
B) is located in Arecibo,Puerto Rico.
C) is a set of optical telescopes linked together to provide very high resolution.
D) is a set of radio telescopes linked together to provide very high resolution.
E) Either answers "c" or "d"

Question 23

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

A) Refracting
B) Reflecting
C) Deflecting
D) Compound
E) Retracting

Question 24

CCD stands for a

A) photometer.
B) charge-coupled device.
C) spectrograph.
D) core collapse device.
E) grating.

Question 25

Observations of radio waves from astronomical objects suffer from poorer resolution than visible observations with the same size dish (or mirror)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.
E) radio telescopes don't use solid mirrors.

Question 26

The main reason for building large optical telescopes on the Earth's surface is

A) that there is a lot of money in science that needs to get spent.
B) to collect as much light as possible from faint objects.
C) to nullify the blurring effects of the Earth's atmosphere and thus produce higher resolution images.
D) to bring astronomical objects closer to make them brighter.
E) that the warm temperatures of the Earth's surface allow for easier telescope operation.

Question 27

Each photon a radio telescope collects has less energy than a visible light photon because radio photons

A) have shorter wavelengths than visible light
B) are not electromagnetic radiation.
C) have longer wavelengths than visible light
D) a and b
E) none of the above

Question 28

What statement below best describes the behavior of light encountering the objective lens of a refracting telescope?

A) All light is absorbed as it travels though a dense,transparent material.
B) White light from astronomical objects is emitted by the lens.
C) Light rays are focussed to form an image after they pass through the lens which is of different optical density.
D) Light rays are focussed to form an image after they reflect off the lens.

Question 29

Infra-red space telescopes must have their mirror cooled to very low temperatures because otherwise it would thermally emit too much ____ itself.

A) infra-red radiation
B) radio waves
C) X-waves
D) gamma rays
E) all of the above

Question 30

In a reflecting telescope the objective is a ____.

A) prism
B) mirror
C) lens
D) diffraction grating
E) photographic plate

Question 31

____ penetrate(s)the Earth's atmosphere to reach its surface.

A) X-rays
B) Radio waves
C) Visible light
D) Answers a and b
E) Answers b and c

Question 32

A ____ is used to produce and analyze a spectrum.

A) photo
B) spectrograph
C) photometer
D) charge-coupled device

Question 33

A ____ has a few million light sensitive diodes in an array about a half-inch square.

A) photometer
B) charge-coupled device
C) spectrograph
D) photographic plate
E) grating

Question 34

In contrast to visual light telescopes,radio telescopes are important in astronomy because they

A) can detect cool hydrogen.
B) have high magnification.
C) can detect stars
D) detect electromagnetic radiation
E) can detect blue light

Question 35

Chromatic aberration occurs in a ____ telescope when

A) reflecting; different colors of light do not focus at the same point.
B) refracting; different colors of light do not focus at the same point.
C) reflecting; light of different wavelengths get absorbed by the mirror.
D) refracting; light of different wavelengths get absorbed by the lens.

Question 36

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

A) to observe more objects in a shorter amount of time.
B) provide a backup system if one or more of the telescopes go down.
C) to produce higher resolution images.
D) to avoid interference between signals from the separate telescopes.
E) to account for the motion of objects in the sky as a result of the Earth's rotation.

Question 37

A ____ is a piece of glass or metal with many small parallel lines etched on its surface.

A) grating
B) spectrograph
C) photometer
D) charge-coupled device
E) prism

Question 38

The light-gathering power of a telescope is directly proportional to

A) the area of the primary mirror or lens.
B) the focal length of the primary mirror or lens.
C) the ratio of the focal lengths of its primary mirror or lens and its eyepiece.
D) the length of the telescope tube.
E) the diameter of the eyepiece.

Question 39

The Hubble Space Telescope objective mirror is not affected by

A) bad seeing.
B) chromatic aberration.
C) diffraction.
D) Answers b and c
E) Answers a and b

Question 40

Radio telescopes with dishes are ____ telescopes.

A) Reflecting
B) Refracting
C) Deflecting
D) Compound
E) Retracting

Question 41

All radio telescopes are refracting telescopes.

Question 42

A larger objective lens shows ____________ a smaller objective lens.

A) more detail than
B) less detail than
C) the same amount of detail as

Question 43

The resolving power of a telescope is ____.

A) a measure of the minimum angular separation between objects or details that can be seen with the telescope.
B) a measure of the maximum angular separation between objects or details 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 faint an object can be seen in the telescope.

Question 44

Which of the items below is electromagnetic radiation? ...

A) gamma ray
B) x-ray
C) visible light
D) radio
E) all of the above

Question 45

X-rays easily penetrate Earth's atmosphere and reach the ground from space.

Question 46

A convex lens is located at "B" and a light sources between "D" and "C".Where will an image of the light source form in the sketch?

A) A
B) B
C) C
D) D

Question 47

One of the advantages of charge-coupled devices over photographic plates is that a CCD can record bright and faint objects on the same exposure.

Question 48

Which of the waves below has the shortest wavelength?

A) gamma ray
B) x-ray
C) visible light
D) infrared
E) radio

Question 49

The largest optical telescope ever constructed was a refracting telescope.

Question 50

Which 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.
E) Both b and c since they have the same focal length

Question 51

The light-gathering power of a telescope increases as the size of the objective increases.

Question 52

Compared to a smaller objective lens,a larger objective lens makes a star's image ...

A) brighter
B) dimmer
C) no effect

Question 53

Telescopes observing in the far ultraviolet work effectively from the tops of mountains.

Question 54

Reflecting telescopes are no longer popular with astronomers because they are expensive and suffer from chromatic aberration.

Question 55

The amount of energy a photon carries depends on its wavelength.

Question 56

Which blurs our earth-based view of celestial objects?

A) the sun
B) the moon
C) the earth's atmosphere

Question 57

Reflecting telescope objectives here on Earth do not have a problem with ...

A) "seeing"
B) diffraction
C) color fringes on the image
D) all of the above

Question 58

Light with a wavelength of 300 nm has a lower frequency than light with a wavelength of 500 nm.

Question 59

An ordinary glass lens forms an image by ____________ of light.

A) reflection
B) refraction
C) diffraction

Question 60

Light can behave as a particle or as a wave.

Question 61

____________________ are subatomic particles traveling a tremendous velocities.

Question 62

A(n)____________________ is used to measure the brightness and color of stars.

Question 63

In contrast to a reflecting telescope,a refracting telescope suffers from ____________________ aberration.

Question 64

The ____________________ is a measure of the clarity of the atmosphere.

Question 65

A(n)____________________ telescope has an objective that is a lens.