Deck 27: Optical Instruments

Question 1

Farsightedness can be corrected with a converging lens.

Answer 1

True

Question 2

A magnifying glass can be made from a diverging lens.

Answer 2

False

Question 3

The focal length of the lens of a simple camera is 40 mm. In what direction must the lens be moved to change the focus of the camera from a person 25 m away to a person 4.0 m away?

A) does not make any difference
B) sideways from the film
C) away from the film
D) towards the film

Answer 3

away from the film

Question 4

The refractive power of a lens used as a magnifying glass is negative.

Question 5

The lens in a person's eye is too thick. The condition that this person has is called

A) farsightedness.
B) spherical aberration.
C) astigmatism.
D) chromatic aberration.
E) nearsightedness.

Question 6

The amount of light reaching the film in a camera is determined by the

A) shutter speed.
B) f-stop.
C) focal length of the lens..
D) focusing.
E) diameter of the aperture.

Question 7

In a compound microscope the final image is virtual.

Question 8

Nearsightedness can be corrected with a diverging lens.

Question 9

In a nearsighted person the eye makes the light coming into it converge too rapidly.

Question 10

The near point of a normal human eye is infinity.

Question 11

Chromatic aberration can be corrected by combining two or more lenses to form a compound lens.

Question 12

The far point of a normal human eye is infinity.

Question 13

A magnifying glass produces a virtual image.

Question 14

A person with a longer near point can see an object as closely with the unaided eye as can a person with the shorter near point.

Question 15

The difference between a camera and the human eye is that a camera utilizes a fixed focal length lens and the eye does not.

Question 16

The length of time the shutter is open when the film is exposed in a camera is determined by the

A) shutter speed.
B) f-stop.
C) focal length of the lens..
D) focusing.
E) diameter of the aperture.

Question 17

In a compound microscope the final image is formed by the objective.

Question 18

The process of changing the shape of the lens, and hence adjusting its focal length, is referred as accommodation.

Question 19

The focal length of the objective of a telescope is much longer than the focal length of the eyepiece.

Question 20

The focal length of the objective in a microscope is very small as compared to the focal length of the eyepiece.

Question 21

Which one of the following is true regarding spherical aberration?

A) It is related to the focal length of the lens.
B) It is related to the diameter of the lens.
C) It is related to the dispersion of light through the lens.
D) It is related to the medium in which a lens is placed.
E) It is related to the shape of the lens.

Question 22

Spherical lenses suffer from

A) both spherical and chromatic aberration.
B) spherical aberration, but not chromatic aberration.
C) chromatic aberration, but not spherical aberration.
D) neither spherical nor chromatic aberration.

Question 23

Nearsightedness can usually be corrected with

A) converging lenses.
B) diverging lenses.
C) achromatic lenses.
D) cylindrical lenses.
E) spherical lenses.

Question 24

The back of a person's eye is too close to the lens. This person is suffering from

A) nearsightedness.
B) spherical aberration.
C) astigmatism.
D) chromatic aberration.
E) farsightedness.

Question 25

Which one of the following is a characteristic of a compound microscope?

A) The objective is a diverging lens.
B) The eyepiece is a diverging lens.
C) The final image is real.
D) The image formed by the objective is virtual.
E) The image formed by the objective is real.

Question 26

A simple refracting telescope provides large magnification by employing

A) a short focal length objective and a short focal length eyepiece.
B) a short focal length objective and a long focal length eyepiece.
C) a long focal length objective and a short focal length eyepiece.
D) a long focal length objective and a long focal length eyepiece.

Question 27

The chromatic aberration in lenses is due to the

A) reflection of light by the lens.
B) refraction of light by the lens.
C) dispersion of light by the lens.
D) polarization of light by the lens.
E) None of the other choices is correct.

Question 28

Which one of the following is not a characteristic of a simple two-lens astronomical refracting telescope?

A) The angular size of the final image is larger than that of the object.
B) The final image is virtual.
C) The objective forms a virtual image.
D) The final image is inverted.

Question 29

Farsightedness can usually be corrected with

A) cylindrical lenses.
B) achromatic lenses.
C) diverging lenses.
D) converging lenses.
E) spherical lenses.

Question 30

A simple compound microscope provides large magnification by employing

A) a short focal length objective and a short focal length eyepiece.
B) a short focal length objective and a long focal length eyepiece.
C) a long focal length objective and a short focal length eyepiece.
D) a long focal length objective and a long focal length eyepiece.

Question 31

The deviation of a lens from its ideal behavior is referred to as

A) spherical aberration.
B) chromatic aberration.
C) an aberration.
D) achromatic aberration.
E) None of the other choices is correct.

Question 32

You are given two converging lenses to build a compound microscope. Lens A has focal length 0.50 cm and lens B has focal length of 3.0 cm. Which of the two lenses would you use for the objective?

A) Lens A, because it has the shorter focal length.
B) Lens B, because it has the longer focal length.
C) It makes no difference which lens I use for the objective.
D) None, because the objective should be a diverging lens.

Question 33

Do mirrors suffer from chromatic aberration?

A) Yes, every optical instrument suffers from it.
B) Yes, because of their specular dispersion.
C) No, because the angle of reflection is always equal to the angle of incidence.
D) None of the previous choices is correct.

Question 34

Jack and Mary view the same microorganism through the same compound microscope. Mary's near point distance, N_M, is twice as large as Jack's near point distance, N_J. If Mary sees the micro-organism with magnification M_M, the magnification with which Jack sees it is

A) 2 M_M.
B) M_M /2.
C) 4 M_M.
D) M_M /4.
E) 8 M_M.

Question 35

You have a choice between two lenses of focal lengths f_a and f_b = 2 f_a to use as objective lens in building a refracting telescope. If the magnification you obtain using lens A is M_a, what will be the magnification when using lens B?

A) M_b = 2 M_a
B) M_b = 4 M_a
C) M_b = 8 M_a
D) M_b = M_a /4
E) M_b = M_a /2

Question 36

What type of lens is a magnifying glass?

A) converging
B) diverging
C) spherical
D) cylindrical
E) achromatic

Question 37

Spherical mirrors suffer from

A) both spherical and chromatic aberration.
B) spherical aberration, but not chromatic aberration.
C) chromatic aberration, but not spherical aberration.
D) neither spherical nor chromatic aberration.

Question 38

Which one of the following is a correct statement?

A) The image formed by the objective of a microscope is smaller than the object.
B) The image formed by the objective lens of a telescope is larger than the object.
C) The image formed by the eyepiece is real for both a microscope and a telescope.
D) The image formed by the objective lens of a microscope is larger than the object.

Question 39

You have a choice between two lenses of focal lengths f_a and f_b = 2 f_a to use as objective lens in building a compound microscope. If the magnification you obtain using lens A is M_a, what will be the magnification when using lens B?

A) M_b = 2 M_a
B) M_b = 4 M_a
C) M_b = 8 M_a
D) M_b = M_a /4
E) M_b = M_a /2

Question 40

A little known fact is that both Robinson Crusoe and Friday wore eyeglasses. As it so happens, Robinson Crusoe was farsighted while Friday was nearsighted. Whose eyeglasses did they use whenever they wanted to start a fire by focusing the Sun's rays?

A) Robinson Crusoe's
B) Friday's
C) Both would work equally well.
D) Both actually worked, but Friday's was a little bit better.
E) Neither's worked, they were in possession of matches.

Question 41

A camera lens has a focal length of 50.0 mm and an aperture setting of 4.00. What is the aperture diameter of this lens?

A) 12.5 mm
B) 10.1 mm
C) 13.6 mm
D) 14.2 mm
E) 15.0 mm

Question 42

A person uses corrective glasses of power -8.5 D.
(a) Is this person nearsighted or farsighted?
(b) If the glasses are worn 2.0 cm from the eye, what is the person's far point without glasses?

Question 43

A magnifying glass of focal length 150. mm is used to examine an old manuscript.
(a) What is the maximum magnification given by the lens?
(b) What is the magnification for relaxed eye-viewing (image at infinity)?

Question 44

A student wishes to build a telescope. She has available an eyepiece of focal length -5.0 cm. What focal length objective is needed to obtain a magnification of 10x?

Question 45

What is the maximum angular magnification of a magnifying glass of focal length 10 cm?
(Assume the near point is at 25 cm.)

Question 46

What is the power of a lens that has a focal length of -40 cm?

A) -2.5 diopters
B) -4.0 diopters
C) +4.0 diopters
D) +2.5 diopters
E) +2.7 diopters

Question 47

A terrestrial telescope has focal lengths of 15. mm, 7.5 cm, and 120. cm for eyepiece, erecting lens, and objective respectively.
(a) What is the magnification of the telescope?
(b) Is this an angular magnification or a lateral size magnification?
(c) What is its length (objective to eyepiece distance)?

Question 48

A person is nearsighted with a near point of 75. cm.
(a) What FOCAL LENGTH is this?
(b) What POWER lens is needed to correct their nearsightedness (assuming distance from lens to eye is negligible)?

Question 49

A nearsighted person has a near point of 12. cm and a far point of 17. cm. If the lens is 2.0 cm from the eye:
(a) what lens power will enable this person to see distant objects clearly?
(b) what then will be the new near point?

Question 50

The focal length of a thin lens is 40 mm and its aperture diameter is 10 mm. What is the f-number of this lens?

A) 4.0
B) 2.0
C) 5.6
D) 0.30
E) 0.40

Question 51

The focal length of the lens of a simple camera is 40.0 mm. How far must the lens be moved to change the focus of the camera from a person 25 m away to one that is 4.0 m away?

A) 0.2 mm
B) 0.3 mm
C) 0.4 mm
D) 0.5 mm
E) 0.7 mm

Question 52

Consider a magnifying glass with a power of 3.0 D.
(a) What is the maximum magnification for a person with a near point of 25. cm?
(b) What is the magnification when viewing with a relaxed eye?

Question 53

What is the resolution limit at 400. nm, due to diffraction, of the Hubble Space Telescope which has an aperture of 2.4 meters?

Question 54

A person's eye lens is 2.7 cm away from the retina. What must the focal length of this lens be in order for an object placed at the near point (N = 25.0 cm) of the eye to focus on the retina?

A) -3.4 cm
B) -2.4 cm
C) 2.4 cm
D) 3.4 cm
E) 2.6 cm

Question 55

A person's eye lens is 2.8 cm away from the retina. What must the focal length of this lens be in order for an object placed at the far point of the eye to focus on the retina?

A) -2.8 cm
B) 2.8 cm
C) -2.4 cm
D) 2.4 cm
E) 2.2 cm

Question 56

A refracting telescope has an eyepiece of focal length -80. mm and an objective of focal length 36. cm. What is the magnification?

Question 57

An objective lens of a telescope has a 1.90 m focal length. When viewed through this telescope, the moon appears 5.25 times larger than normal. How far apart are the objective lens and the eyepiece when this instrument is focused on the moon?

Question 58

The world's largest refracting telescope is operated at the Yerkes Observatory in Wisconsin. It has an objective of diameter of 1.02 m. Suppose such an instrument could be mounted on a spy satellite at an elevation of 300. km above the surface of the Earth. What is the minimum separation of two objects on the ground if their images are to be clearly resolved by this lens?
(Assume an average wavelength of 0.55 μm for white light.)

Question 59

What is the focal length of the corrective contact lens needed by a nearsighted person whose far point is 60 cm?

A) -60 cm
B) -30 cm
C) +30 cm
D) +60 cm
E) +130 cm

Question 60

What is the power of the lens that has a focal length of 40 cm?

A) -2.5 diopters
B) -4.0 diopters
C) +4.0 diopters
D) +2.5 diopters
E) +2.7 diopters

Question 61

John is nearsighted and cannot see things beyond 110 cm from his eyes. What is the focal length of the contact lenses that will enable him to see distant objects clearly?

A) +50 cm
B) -50 cm
C) -110 cm
D) +110 cm
E) -30 cm

Question 62

The power of a lens is 4.0 diopters. What is the focal length of this lens?

A) 25 cm
B) 55 cm
C) 40 cm
D) 20 cm
E) 60 cm

Question 63

The near point of a farsighted person is 65 cm. What power contact lens must he use to correct this problem and be able to read a book at a normal near point of 25 cm?

A) -4.2 diopters
B) -2.5 diopters
C) -2.4 diopters
D) 4.2 diopters
E) 2.5 diopters

Question 64

What power contact lens should be used to correct the vision of a farsighted person whose near point is 80 cm to see something clearly at a distance of 25 cm?

A) 2.8 diopters
B) -2.8 diopters
C) -4.0 diopters
D) -4.2 diopters
E) 4.2 diopters

Question 65

A nearsighted person has a far point that is 4.2 m from his eyes. What focal length lenses must he use in his contact lenses to allow him to focus on distant objects?

A) -4.2 m
B) 4.2 m
C) -5.2 m
D) 5.2 m
E) 4.8 m

Question 66

The focal length of a lens is 5 m. What is the refractive power of this lens in diopters?

A) 0.1 diopters
B) 0.2 diopters
C) 0.3 diopters
D) 0.4 diopters
E) 0.5 diopters

Question 67

A magnifying glass produces an angular magnification of 7. What is the focal length of this lens if a person whose near point is 28 cm reads a book using this magnifying glass?

A) 2 cm
B) 3 cm
C) 4 cm
D) 5 cm
E) 6 cm

Question 68

A nearsighted person has a far point that is 4.2 m from his eyes. What focal length lenses in diopters he must use in his contacts to allow him to focus on distant objects?

A) 0.48 diopters
B) -0.48 diopters
C) -0.36 diopters
D) -0.24 diopters
E) 0.24 diopters

Question 69

A nearsighted person cannot see objects beyond 80 cm from his eyes. Which one of the following combinations represents the correct focal length and the refractive power of the contact lenses that will enable him to see the distant objects clearly?

A) +80 cm, +1.3 diopters
B) -80 cm, +1.3 diopters
C) +80 cm, -1.3 diopters
D) -80 cm, -1.3 diopters
E) -1.3 cm, +1.3 diopters

Question 70

What is the power of the combined lenses with individual powers of 8.0 diopters and 4.0 diopters?

A) 32 diopters
B) 24 diopters
C) 2.0 diopters
D) 4.0 diopters
E) 12 diopters

Question 71

John is nearsighted and cannot see things beyond 90 cm from his eyes. What is the refractive power of the contact lenses that will enable him to see distant objects clearly?

A) +1.1 diopters
B) -1.1 diopters
C) -1.7 diopters
D) -2.2 diopters
E) +2.2 diopters

Question 72

What is the focal length of the combined lenses with individual powers of 8.0 diopters and 4.0 diopters?

A) 8.0 cm
B) 5.6 cm
C) 6.0 cm
D) 8.3 cm
E) 4.0 cm

Question 73

What is the focal length of a pair of contact lenses that will allow a person with a near point of 125.0 cm to read a newspaper held 25.0 cm from his eyes?

A) -100 cm
B) -31.3 cm
C) 10.2 cm
D) 20.8 cm
E) 31.3 cm

Question 74

Jill is farsighted and cannot see objects clearly that are closer to the eye than 80.0 cm. What is the focal length of the contact lenses that will enable her to see objects at a distance of 25.0 cm from her eyes?

A) +36.4 cm
B) -36.4 cm
C) -21.2 cm
D) +21.2 cm
E) +32.5 cm

Question 75

A far sighted person can not see clearly objects that are closer to his eyes than 60.0 cm. Which one of the following combinations represents the correct focal length and the refractive power of the contact lenses that will enable him to see the objects at a distance of 25.0 cm from his eyes?

A) -42.9 cm, +2.33 diopters
B) -42.9 cm, -2.33 diopters
C) +42.9 cm, +2.33 diopters
D) +42.9 cm, -2.33 diopters
E) +60 cm, +42.9 diopters

Question 76

The focal length of a magnifying glass is 15 cm. If the near point of a person is 25 cm, what is the magnification of this glass for this person when his eyes are focused at infinity?

A) 1.7
B) 2.7
C) 3.7
D) 4.7
E) 5.7

Question 77

A person can read the newspaper when it is held at 60 cm from his eyes. What should the focal length of his contact lenses be to allow him to read the newspaper comfortably at a distance of 30 cm?

A) -30 cm
B) +30 cm
C) -60 cm
D) +60 cm
E) +90 cm

Question 78

What is the near point of a farsighted person who can read a newspaper held 25 cm from his eyes when he wears 3.33 diopters glasses?

A) 1.5 m
B) 0.50 m
C) 1.9 m
D) 0.75 m
E) 0.60 m

Question 79

What power contact lens must be used to correct the vision of a nearsighted person whose far point is 40 cm?

A) 2.5 diopters
B) -2.5 diopters
C) -3.6 diopters
D) -4.0 diopters
E) 4.0 diopters

Question 80

Jill is farsighted and cannot see objects clearly that are closer to the eye than 80.0 cm. What is the refractive power of the contact lenses that will enable her to see objects at a distance of 25.0 cm from her eyes?

A) +2.75 diopters
B) -2.75 diopters
C) -4.72 diopters
D) +4.72 diopters
E) +7.00 diopters