Deck 27: Optical Instruments

Question 1

Farsightedness can usually be corrected with

A)converging lenses.
B)diverging lenses.
C)convex mirrors.
D)cylindrical lenses.
E)concave mirrors.

Answer 1

converging lenses.

Question 2

What type of lens is used to make a magnifying glass?

A)converging
B)diverging
C)Either type would work equally well.

Answer 2

converging

Question 3

To maximize the magnification of a refracting telescope,what lenses should you choose?

A)The objective lens and eyepiece should both have small focal lengths.
B)The objective lens and eyepiece should both have large focal lengths.
C)The objective lens should have a small focal length and the eyepiece should have a large focal length.
D)The objective lens should have a large focal length and the eyepiece should have a small focal length.
E)The objective lens should have a large focal length,but it doesn't matter what the focal length of the eyepiece is.

Answer 3

The objective lens should have a large focal length and the eyepiece should have a small focal length.

Question 4

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,but fortunately they were in possession of matches.

Question 5

Which one of the following statements is correct?

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 6

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 7

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 8

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 one 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 9

A simple compound microscope normally uses

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

Question 10

Which one of the following is normally not a characteristic of a simple two-lens refracting astronomical 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 11

If the lens in a person's eye is too highly curved,this person is suffering from

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

Question 12

You have a choice between two lenses of focal lengths f_a and f_b,where f_b = 2f_a,to use as the 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 13

The focal length of the lens of a simple digital camera is 40 mm,and it is originally focused on a person 25 m away.In what direction must the lens be moved to change the focus of the camera to a person 4.0 m away?

A)It does not make any difference.
B)sideways from the CCD sensors
C)away from the CCD sensors
D)towards the CCD sensors

Question 14

You have a choice between two lenses of focal lengths f_a and f_b,where f_b = 2f_a,to use as the 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 15

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 microorganism with magnification M_M,with what magnification does Jack see it?

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

Question 16

If 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 17

The closest object that a typical young person with normal vision can focus on clearly is closest to

A)1 cm.
B)10 cm.
C)25 cm.
D)50 cm.
E)75 cm.

Question 18

In a compound microscope

A)both the objective and the eyepiece form real images.
B)magnification is provided by the objective lens and not by the eyepiece.The eyepiece merely increases the resolution of the image viewed.
C)magnification is provided by the objective and not by the eyepiece.The eyepiece merely increases the brightness of the image viewed.
D)the magnification is m₁ + M₂,where m₁ is the lateral magnification of the objective and M₂ is the angular magnification of the eyepiece.
E)the image of the objective serves as the object for the eyepiece.

Question 19

For relaxed viewing with a microscope or a telescope,the eyepiece is adjusted to place the image at

A)the near point of the eye.
B)the pupil of the eye.
C)the focal point of the eyepiece.
D)infinity.
E)the focal point of the objective lens.

Question 20

Nearsightedness is usually corrected with

A)converging lenses.
B)diverging lenses.
C)convex mirrors.
D)cylindrical lenses.
E)concave mirrors.

Question 21

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 22

A person's near point is 25 cm,and her eye lens is 2.7 cm away from the retina.What must be the focal length of this lens for an object at the near point 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 23

Which of the following statements are correct? (There could be more than one correct choice. )

A)Spherical aberration,but not chromatic aberration,occurs for lenses.
B)Chromatic aberration,but not spherical aberration,occurs for lenses.
C)Both chromatic aberration and spherical aberration occur for lenses.
D)Both chromatic aberration and spherical aberration occur for spherical mirrors.

Question 24

A farsighted girl has a near point at 2.0 m but has forgotten her glasses at home.The girl borrows eyeglasses that have a power of +2.75 diopters.With these eyeglasses,what is the near point of the girl,assuming that she wears them extremely close to her eyes?

A)28 cm
B)31 cm
C)33 cm
D)37 cm
E)40 cm

Question 25

A person's eye lens is 2.8 cm from the retina,and his near point is at 25 cm.What must be the focal length of his eye lens so that an object at the far point of the eye will 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 26

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 27

A myopic (nearsighted)child wears contact lenses that allow her to have clear distant vision.The power of the lenses of her eyeglasses is -3.00 diopters.Without the corrective lenses,what is the far point of the girl?

A)0.33 m
B)0.25 m
C)0.17 m
D)0.42 m
E)0.50 m

Question 28

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 29

What is the power of a lens that has a focal length of -40 cm and a width of 2.0 cm?

A)-2.5 diopters
B)-0.50 diopters
C)+4.0 diopters
D)+2.5 diopters
E)-50 diopters

Question 30

A refracting telescope has a magnification M.If the focal length of the objective lens is doubled and the eyepiece focal length is halved,what is the new magnification?

A)4M
B)2M
C)M/2
D)M/4
E)M

Question 31

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 very distant mountains?

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

Question 32

A farsighted boy has a near point at 2.3 m and requires contact lenses to correct his vision to the normal near point.What is the correct choice of lens power for the contact lenses?

A)-0.28 diopters
B)+0.28 diopters
C)-3.6 diopters
D)+3.6 diopters
E)+1.8 diopters

Question 33

What is the power of the lens that has a focal length of 40 cm and a diameter if 5.0 cm?

A)-2.5 diopters
B)+20 diopters
C)+0.20 diopters
D)+2.5 diopters
E)+2.7 diopters

Question 34

A simple digital camera lens with focal length
Perfectly focuses the image of an object on a CCD sensor located a distance
Away from the lens.The object now moves away from the lens and the new distance between the lens and sensor is
(a)By what amount did the object change its distance from the lens?
(b)What is the new magnification?

A)(a)0.08 cm (b)3.33
B)(a)0.03 cm (b)0.30
C)(a)990.00 cm (b)0.23
D)(a)12.22 cm (b)4.33

Question 35

The focal length of the lens of a simple film camera is 40.0 mm.By what amount should the distance between the lens and the film be increased or decreased to change the focus from a person who is 25 m from the lens to one who is 4.0 m from the lens?

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

Question 36

A 35-mm camera equipped with a 40-mm focal length lens is used to photograph a tree 17 m tall.If a 32-mm high image of the tree on the CCD sensor is required,how far should the camera lens be from the tree?

A)21 m
B)22 m
C)23 m
D)24 m
E)26 m

Question 37

The power of a lens is 4.0 diopters and its diameter is 5.0 cm.What is the focal length of this lens?

A)25 cm
B)55 cm
C)10 cm
D)0.25 cm
E)2.5 cm

Question 38

A machinist with normal vision has a near point at 25 cm.This machinist wears +4.25-diopter eyeglasses in order to do very close work.With these eyeglasses,what is the near point of the machinist? Assume that he wears the glasses extremely close to his eyes.

A)12 cm
B)10 cm
C)7 cm
D)15 cm
E)17 cm

Question 39

As a treatment for cataracts (a cloudiness of the lens of the eye),the natural lens is removed and a plastic lens is implanted.After this is done a person can see distant objects clearly,but he cannot accommodate to focus on nearby objects.If such a person wanted to read a book at a distance of 25 cm,he would have to wear contact lenses having a diopter power of

A)+2.78 diopters.
B)+3.33 diopters.
C)-1.78 diopters.
D)+4.00 diopters.
E)-4.00 diopters.

Question 40

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

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

Question 41

A person cannot see clearly objects more than 70.0 cm away.What power of corrective lens should be prescribed if the glass is to be worn 1.00 cm in front of the eye?

A)1.45 diopters
B)-1.45 diopters
C)0.0145 diopters
D)-0.0145 diopters

Question 42

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 43

A nearsighted person has a far point that is 4.2 m from his eyes.What power contact lenses must he wear to allow him to focus on distant mountains?

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

Question 44

Diego 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 comfortably see distant hills clearly?

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

Question 45

A nearsighted person has a far point of 18 cm.What power contact lenses will allow this person to comfortably see distant objects clearly?

A)+5.6 diopters
B)-5.6 diopters
C)+0.056 diopters
D)-0.056 diopters

Question 46

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

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

Question 47

The focal length of a converging lens is 10 cm.What is the angular magnification of this lens if the image is viewed by a relaxed eye with a near point of 25 cm?

A)0.50
B)1.5
C)2.5
D)3.5
E)4.5

Question 48

What is the focal length of a contact lens that will allow a person with a near point of 125 cm to read a physics book 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 49

When a person with a near point at 28 cm uses a certain magnifying glass,it produces an angular magnification of 7.0 with the image very distant.What is the focal length of the lens of this magnifying glass?

A)2.0 cm
B)3.0 cm
C)4.0 cm
D)5.0 cm
E)6.0 cm

Question 50

A farsighted person cannot see clearly objects that are closer to her 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 her to comfortably see the objects at a distance of 25.0 cm from her 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 51

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 comfortably 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 52

What power contact lens should be used to correct the vision of a farsighted person whose near point is 80 cm so she can see things clearly that are 25 cm in front of her?

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

Question 53

A nearsighted person wears contact lenses having a power of -0.15 diopters.What is the person's uncorrected far point?

A)1.5 m
B)3.3 m
C)6.0 m
D)6.7 m

Question 54

What is the uncorrected near point of a farsighted person who can comfortably read a newspaper held 25 cm from his eyes when he wears +3.33-diopter contact lenses?

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

Question 55

Without glasses,a person can comfortably read a magazine when it is held at 60 cm from his eyes.What should be the focal length of his contact lenses to allow him to read the magazine comfortably at a distance of 30 cm?

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

Question 56

The near point of a farsighted person is 100 cm.She places reading glasses very close to her eyes,and with them she can comfortably read a book at a distance of 25 cm.What is the power of the lenses in her reading glasses?

A)+2.5 diopters
B)+3.0 diopters
C)+3.2 diopters
D)-2.0 diopters

Question 57

What power contact lens is needed to correct for farsightedness where the uncorrected near point is 75 cm?

A)+2.7 D
B)-2.7 D
C)+5.3 D
D)-5.3 D

Question 58

The focal length of a magnifying glass is 15 cm.If the near point of a person is 25 cm,what is the angular magnification of the 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 59

Alice is farsighted and cannot see objects clearly that are closer to her eye than 80.0 cm.What is the refractive power of the contact lenses that will enable her to comfortably 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

Question 60

Olga is nearsighted and cannot see things beyond 90 cm cm from her eyes.What is the refractive power of the contact lenses that will enable her to comfortably see distant buildings clearly?

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

Question 61

A very delicate sample is placed 0.150 cm from the objective lens of a microscope.The focal length of the objective is 0.140 cm,and that of the eyepiece is 1.0 cm.The near-point distance of the person using the microscope is 25.0 cm.The magnitude of the final magnification of the microscope is closes to

A)375.
B)300.
C)250.
D)125.
E)100.

Question 62

The focal lengths of the objective lens and the eyepiece of a microscope are 0.50 cm and 2.0 cm,respectively,and their separation is 6.0 cm when adjusted for minimum eyestrain for a person with a near point of 25.0 cm.If the microscope is focused on a small object,the magnitude of its final overall magnification is closest to

A)50.
B)100.
C)150.
D)200.
E)250.

Question 63

A person having a near point of 25 cm uses a magnifying glass with a focal length of 10 cm.What is the angular magnification of the glass for that person when her eyes are focused at infinity?

A)1.5
B)2.5
C)3.5
D)4.5

Question 64

A person uses a converging lens of focal length 5.0 cm as a magnifying glass.What is the angular magnification if the person's eye is relaxed and has a near point of 25 cm?

A)4.0
B)5.0
C)6.0
D)7.0

Question 65

The objective lens of a microscope has a focal length of 2.4 mm and the eyepiece has an angular magnification of 15.The object is positioned 0.060 mm beyond the focal point of the objective.The focal point of the eyepiece is positioned at the real image formed by the objective.The near point of the microscope user is at 25 cm.What is the distance between the objective lens and the eyepiece?

A)98 mm
B)102 mm
C)107 mm
D)111 mm
E)115 mm

Question 66

A lens of focal length 90 mm is used as a magnifier by a person with a near point of 25 cm.The object being viewed is 9.9 mm long,and is positioned at the focal point of the lens.What is the angle subtended by the image at infinity,in milliradians?

A)110 mrad
B)73 mrad
C)37 mrad
D)147 mrad
E)183 mrad

Question 67

The focal lengths of the objective lens and the eyepiece of a microscope are 0.50 cm and 2.0 cm,respectively,and their separation adjusted for minimum eyestrain is 6.0 cm.If the microscope is focused on a small object,what is the distance between the object and the objective lens?

A)0.31 cm
B)0.42 cm
C)0.49 cm
D)0.57 cm
E)0.73 cm

Question 68

A magnifying glass uses a converging lens with a refractive power of 20 diopters.What is the angular magnification if the image is to be viewed by a relaxed eye with a near point of 25 cm?

A)5.0
B)3.0
C)4.0
D)1.0
E)2.0

Question 69

The distance between the object to be viewed and the eyepiece of a compound microscope is 25.0 cm.The focal length of its objective lens is 0.200 cm and the eyepiece has a focal length of 2.60 cm.What is the magnitude of the total magnification of the microscope when used by the person of normal eyesight if it is designed for minimum eyestrain?

A)1070
B)204
C)520
D)477
E)772

Question 70

The focal lengths of the objective lens and the eyepiece in a microscope are 0.29 cm and 2.50 cm,respectively.An object is placed at 0.30 cm from the objective lens and the image of this object is viewed with the eyepiece adjusted for minimum eyestrain for persons with a near point of 25 cm.The magnitude of the final overall magnification of the microscope is closest to

A)100.
B)200.
C)300.
D)410.
E)500.

Question 71

A lens of focal length 40 mm is used as a magnifier.The object being viewed is 5.3 mm long,and is positioned at the focal point of the lens.The user of the magnifier has a near point at 25 cm.What is the angular magnification of the magnifier?

A)6.3
B)5.6
C)6.9
D)7.5
E)8.1

Question 72

The objective lens of a microscope has a focal length of 2.4 mm and the eyepiece has an angular magnification of 15.The object is positioned 0.060 mm beyond the focal point of the objective.The focal point of the eyepiece is positioned at the real image formed by the objective.The near point of the microscope user is at 25 cm.The magnitude of the overall magnification of the microscope is closest to

A)400.
B)450.
C)500.
D)550.
E)600.

Question 73

A magnifying glass has a focal length of 7.0 cm.What is the angular magnification if the image is viewed by a person having a relaxed eye with the near point of 25 cm?

A)1.6
B)2.6
C)3.6
D)4.6

Question 74

The distance between the object to be viewed and the eyepiece of a compound microscope is 18.0 cm.The focal length of its objective lens is 0.80 cm and the eyepiece has a focal length of 2.3 cm.The near-point distance of the person using the microscope is 25.0 cm.What is the magnitude of the total magnification of the microscope if it is designed for minimum eyestrain?

A)120
B)184
C)200
D)360
E)480

Question 75

The focal lengths of the objective lens and the eyepiece in a microscope are 2.90 mm and 2.50 cm,respectively.An object is placed 3.00 mm from the objective.The image of this object is viewed with the eyepiece adjusted for minimum eyestrain for persons with a near point of 25 cm.What is the distance between the objective and the eyepiece?

A)9.9 cm
B)9.0 cm
C)15 cm
D)11 cm
E)13 cm

Question 76

A compound microscope has an objective with a focal length of 3.00 mm and an eyepiece of focal length 6.00 cm.It is adjusted for minimum eyestrain for persons with a near point of 25 cm.If the two lenses are separated by 40.0 cm,what is the total overall magnification?

A)28
B)56
C)470
D)550
E)2200

Question 77

A compound microscope has a 18-cm-long barrel and an objective lens with a focal length of 8.0 mm.What is the focal length of the eyepiece to give a total magnification of 240? It is adjusted for minimum eyestrain for persons with a near point of 25 cm.

A)1.3 m
B)1.5 cm
C)1.9 cm
D)2.1 cm
E)2.3 cm

Question 78

What is the angular magnification of a magnifying glass of focal length 4.0 cm if the image is to be viewed by a relaxed eye having a near point of 25 cm?

A)2.0
B)3.0
C)3.6
D)4.0
E)6.3

Question 79

A microscope has an objective lens of focal length 1.40 mm and an eyepiece of focal length 20.00 mm.It is adjusted for minimum eyestrain for persons with a near point of 25.0 cm.A blood sample is placed 1.50 mm from the objective.The magnitude of the overall magnification is closest to

A)18.
B)37.
C)180.
D)370.

Question 80

A microscope has an objective lens of focal length 1.40 mm and an eyepiece of focal length 20.00 mm.It is adjusted for minimum eyestrain for persons with a near point of 25.0 cm.A blood sample is placed 1.50 mm from the objective.How far apart are the lenses?

A)20 mm
B)21 mm
C)23 mm
D)41 mm