Deck 26: Applications of Optics

Question 1

A telescope has an objective lens with a focal length of 90 cm and an eyepiece of focal length 3.0 cm. What is the angular magnification of the telescope?

A) 180
B) 33
C) 60
D) 30

Answer 1

30

Question 2

If the objective lens of a compound microscope is replaced with a lens of double the focal length while the eyepiece also has its focal length halved, what will happen to the overall magnification of the microscope?

A) This will result in no change in the magnification.
B) The magnification quadruples.
C) The magnification doubles.
D) The magnification decreases.

Answer 2

This will result in no change in the magnification.

Question 3

If a person is nearsighted the corrective lens will:

A) take an object at the far point and form an image at 25 cm.
B) take an object at 25 cm and form an image at the far point.
C) take an object at infinity and form an image at the far point.
D) take an object at infinity and form an image at 25 cm.

Answer 3

take an object at infinity and form an image at the far point.

Question 4

A magnifier uses a:

A) diverging lens to form a real image.
B) diverging lens to form a virtual image.
C) converging lens to form a real image.
D) converging lens to form a virtual image.

Question 5

A converging lens will be prescribed by the eye doctor to correct which of the following?

A) glaucoma
B) nearsightedness
C) farsightedness
D) astigmatism

Question 6

A lens with a focal length of 12 cm has what refractive power?

A) 5.0 diopters
B) 9.6 diopters
C) 6.7 diopters
D) 8.3 diopters

Question 7

You are designing contact lenses for someone whose near point is 43 cm. What focal length lens should you prescribe so that an object can be clearly seen when placed at 25 cm in front of the eye?

A) "43 cm"
B) "18 cm"
C) "-15 cm"
D) "60 cm"

Question 8

A compound microscope has an eyepiece that:

A) uses a real image from the objective as the object and forms a virtual image.
B) uses a virtual image from the objective as the object and forms its own virtual image.
C) uses a real image from the objective as the object and forms its own real image.
D) uses a virtual image from the objective as the object and forms its own real image.

Question 9

A magnifying lens of refractive power d (in diopters) gives what magnification when the viewing eye is relaxed assuming a near point of 25 cm?

A) 25d
B) d/4
C) 0.25/d
D) The correct answer is not given.

Question 10

What is the magnitude of the approximate magnification of a compound microscope with objective and eyepiece focal lengths of 0.90 cm and 3.6 cm, respectively, and a separation between lenses of 20 cm?

A) 460
B) 12
C) 20
D) 150

Question 11

A person can see well close up, but cannot do so in the distance. To correct this, lenses that are _____ having a _____ refractive power could be used.

A) thicker at their center than at the edges, positive
B) thicker at their center than at the edges, negative
C) thinner at their center than at the edges, negative
D) thinner at their center than at the edges, positive

Question 12

A nearsighted person cannot see objects clearly beyond 50 cm (the far point). If the patient has no astigmatism and contact lenses are prescribed, what is the power of the lens required to correct the patient's vision?

A) "-2.0 diopters"
B) "-3.3 diopters"
C) "-4.0 diopters"
D) "-5.0 diopters"

Question 13

A lens is used as a magnifier. Which of the following statements is incorrect?

A) The focal length of the lens must be negative.
B) The magnification is greatest when the eye focuses at the near point.
C) The refractive power of the lens is positive.
D) The lens is convex.

Question 14

A given individual is unable to see objects clearly when they are beyond 75 cm. What focal length contact lens should be used to correct this problem?

A) "75 cm"
B) "-75 cm"
C) "-100 cm"
D) "-33.3 cm"

Question 15

While a camera has film where the image is formed, the eye forms the image on the:

A) cornea.
B) optic nerve.
C) pupil.
D) retina.

Question 16

You are building a compound microscope with an objective lens of focal length 1.1 cm and an eyepiece lens of focal length 5.0 cm. You mount the lenses 18 cm apart. What is the approximate magnification of your microscope?

A) 3
B) 7
C) 80
D) 130

Question 17

A simple magnifier makes an image appear at the near point distance from the eye of the viewer (25 cm). What is the magnifying power of the magnifier if it is constructed of a lens of focal length of 6.3 cm? Do not use the approximation formula.

A) 5.0
B) 50
C) 1.2
D) 7.3

Question 18

Which of the following would decrease the magnification of a compound microscope?

A) Replacing the objective lens with one of larger diameter.
B) Replacing the eyepiece lens with one of shorter focal length.
C) Replacing the eyepiece lens with one of smaller diameter.
D) Replacing the objective lens with one of longer focal length.

Question 19

Doubling the focal length of the objective lens of a compound microscope will change the magnification by what factor?

A) 4
B) 1/4
C) 2
D) 1/2

Question 20

A magnifying lens with a focal length of 10 cm has what maximum magnification? (Assume the near point is 25 cm). Do not use the approximation formula.

A) 3.5
B) 2.5
C) 7.1
D) 3.0

Question 21

Doubling the aperture diameter of a camera lens will change the light intensity admitted to the film by what factor?

A) 4.0
B) 0.25
C) 0.50
D) 2.0

Question 22

Why is it easier to see fine print in brighter light than in dimmer light?

A) This is not so, it is easier to see fine print in dimmer light than in brighter light.
B) Because the refractive power of the eye increases as the light intensity increases.
C) In brighter light, the f-number of the eye increases.
D) In brighter light, the longer wavelengths dominate.

Question 23

A camera lens is initially set at f/16 for a shutter speed of 1/30 s. If the amount of lighting on the subject is unchanged, and the lens is set at f/5.6, what is the proper shutter speed at this setting?

A) 1/8 s
B) 1/250 s
C) 1/500 s
D) 1/16 s

Question 24

Increasing the focal length in a telephoto lens by a factor of nine, while keeping the aperture size constant, will change the f-number by what factor?

A) 1/3
B) 1/9
C) 9
D) 3

Question 25

Even relatively small astronomical telescopes are ordinarily not used for terrestrial observation because:

A) their images are not in color.
B) their images are inverted.
C) their images are too bright.
D) their images are too dim.

Question 26

The Palomar reflecting telescope has a parabolic mirror with an 80-m focal length. What is the magnification achieved when an eyepiece of focal length 5.0 cm is used?

A) 1200
B) 800
C) 3200
D) 1600

Question 27

Using a camera with a fixed focal length lens, how will increasing the f-number affect the depth of focus and the intensity of the light reaching the ccd (or film)?

A) The depth of focus will decrease but the intensity of light reaching the ccd will increase.
B) The depth of focus will increase as will the intensity of light reaching the ccd.
C) The depth of focus will increase but the intensity of light reaching the ccd will decrease.
D) The depth of focus will decrease as will the intensity of light reaching the ccd.

Question 28

Unlike the refracting astronomical telescope discussed in the text that gives an inverted image, Galileo's telescope produced an upright image. What did he do differently to accomplish this?

A) He rotated the barrel of the telescope 180°.
B) He used diverging lenses for both the eyepiece and the objective.
C) He used a diverging lens for the eyepiece.
D) He used a diverging lens for the objective.

Question 29

A camera uses a:

A) diverging lens to form an imaginary image.
B) converging lens to form a real image.
C) converging lens to form an imaginary image.
D) diverging lens to form a real image.

Question 30

The eye parts iris, retina, cornea, and ciliary muscle, play roles related to _____, _____, _____, and _____ in a camera.

A) the aperture, the lens, the ccd, focusing
B) the lens, focusing, the ccd, the aperture
C) the lens, the aperture, focusing, the ccd
D) the aperture, the ccd, the lens, focusing

Question 31

When using an eyepiece of focal length f, the Yerkes refracting telescope gives a magnification of 800. What focal length eyepiece would yield a magnification of 500?

A)
B)
C)
D)

Question 32

Doubling the f-number of a camera lens will change the light intensity admitted to the film by what factor?

A) 1/4
B) 4
C) 1/2
D) 2

Question 33

Decreasing the aperture diameter of a camera lens by a factor of three will change the f-number by what factor?

A) 3
B) 9
C) 1/9
D) 1/3

Question 34

A refracting astronomical telescope has objective and eyepiece lenses of focal lengths 38 cm and 0.40 cm, respectively. What is the angular magnification of this instrument?

A) 95
B) 50
C) 27
D) 19.6

Question 35

Halving the focal length of a telephoto lens, while holding aperture size constant, will change the light intensity admitted to the film by what factor?

A) 0.50
B) 2.0
C) 0.25
D) 4.0

Question 36

An astronomical telescope has an objective lens with focal length f_o and has an eyepiece with focal length f_e. A second telescope has objective and eyepiece lenses with half the focal length of the first telescope. Which telescope gives the greater magnification and by what factor?

A) The second telescope gives 4 times the magnification of the first.
B) The first telescope gives 4 times the magnification of the second.
C) The actual focal lengths must be known to answer this question.
D) Both telescopes give the same magnification.

Question 37

The Yerkes refracting telescope has a 1-m diameter objective lens of focal length 20 m and an eyepiece of focal length 2.0 cm. What is the magnification of the planet Mars as seen through this telescope?

A) 800
B) 1000
C) 400
D) 200

Question 38

I take two pictures of my dog Kaycee. I use the same film and level of illumination for both pictures, but I halve the f-number for the second picture. By what factor will the required time of exposure change if the film is to receive the same total light energy?

A) 4.0
B) 0.50
C) 2.0
D) 0.25

Question 39

Changing the f-number of a camera by two stops by going from f/16 to f/8 will change the intensity of the light hitting the film by a factor of:

A) 4
B) 1/2.
C) 1/4.
D) 2.

Question 40

What is the f-number of a camera lens that has an aperture-opening diameter of 0.20 cm and a focal length of 3.0 cm?

A) 10
B) 0.10
C) 15
D) 0.80

Question 41

c. 1/4.
B) 1/2.
D) 2.

Question 42

A high f-number:

A) allows using a slower shutter speed.
B) causes more spherical aberration.
C) allows a larger depth of focus.
D) is not related to any of the above options.

Question 43

An unclad optical fiber has index of refraction 1.40. What is the acceptance angle for this fiber if it is submerged in a fluid with index of refraction 1.30? The acceptance angle is the greatest angle at which the light enters the end of the fiber and still causes total internal reflection.

A) 69.0°
B) 23.6°
C) 45.8°
D) Any angle will be accepted.

Question 44

A camera has a lens that has an adjustable film distance used for focusing purposes. When the object being photographed is at a very large distance, the distance from the lens to the film is 50.0 mm. What would be the lens-to-film distance for an in-focus object 2.00 m from the camera?

A) 66.7 mm
B) 40.0 mm
C) 51.3 mm
D) 48.8 mm

Question 45

A pinhole camera is used to photograph a 23-cm tall object at a distance of 3.0 m, the image being projected on film at a distance of 46 cm from the pinhole. What are the height and orientation of the image?

A) 3.5 cm, upright
B) 3.5 cm, inverted
C) 12 cm, upright
D) 12 cm, inverted

Question 46

The pupil of the eye increases in size under which condition?

A) object viewed is well illuminated
B) eye is focused on a nearby object
C) object viewed is dimly illuminated
D) eye is focused on a distant object

Question 47

An unclad optical fiber has index of refraction 1.70. What is the acceptance angle for this fiber? The acceptance angle is the greatest angle at which the light enters the end of the fiber and still causes total internal reflection.

A) 38.7°
B) 51.3°
C) 39.7°
D) Any angle will be accepted.

Question 48

In the NSOM technique, the letter S stands for:

A) slow.
B) small.
C) scanning.
D) swift.

Question 49

An optical fiber is made with core material of index of refraction 1.6. The fiber is clad with a material of index 1.2. What is the speed of light traveling along the central axis of this fiber?

A) 2.5 *10⁸ m/s
B) 1.9 * 10⁸ m/s
C) 2.0 *10⁸ m/s
D) 3.0 * 10⁸ m/s

Question 50

A camera has a lens of focal length 50 mm and an f-number of 4.0. What is the diameter of the lens?

A) 50 mm
B) 100 mm
C) 25 mm
D) 13 mm

Question 51

A 1.5-m tall woman stands 5.0 m in front of a camera with a 8.0 cm focal length lens. What is the size of the image formed on film?

A) 2.4 cm
B) 0.60 cm
C) 1.9 cm
D) 1.2 cm

Question 52

An optical fiber is made with core material of index of refraction 1.30. The fiber is clad with a material of index 1.50. What is the critical angle for this fiber?

A) 53.1°
B) 56.4°
C) 60.1°
D) With these indices, there is not critical angle.

Question 53

A CD is made with a plastic coating with index of refraction n and is used with a laser that produces a wavelength $\lambda$ in the plastic. Which of the following pit depths would produce the desired destructive interference in this situation?

A) " $\lambda$ /2n"
B) " $\lambda$ /4"
C) " $\lambda$ /4n"
D) " $\lambda$ /2"

Question 54

An optical fiber with index of refraction 1.60 is clad in a material of index 1.30. What is the ratio of the maximum time to the minimum time for light signals to travel down a given length of this fiber?

A) 1.60
B) 1.30
C) 1.23
D) 1.95

Question 55

A camera is used to photograph the full moon, which has an angular diameter of 0.51°. The image on the film is 2.5 mm in diameter. What is the focal length of the lens?

A) 6.3 mm
B) 280 mm
C) 13 mm
D) 450 mm

Question 56

A CD player uses a laser with wavelength 900 nm. If the CD has a plastic coating with index 1.50, what is the wavelength in the plastic?

A) 600 nm
B) 500 nm
C) 1350 nm
D) 750 nm