Deck 33: Lenses and Optical Instruments

Question 1

A convex lens is known as a diverging lens and a concave lens is known as a converging lens.

Answer 1

False

Question 2

Nearsightedness can be corrected with a diverging lens.

Answer 2

True

Question 3

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

Answer 3

True

Question 4

In a compound microscope the final image is virtual.

Question 5

State how to draw the three rays for finding the image position due to a thin lens.

Question 6

A convex lens always produces a virtual image.

Question 7

The far point of a normal human eye is infinity.

Question 8

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

Question 9

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

Question 10

A magnifying glass produces a virtual image.

Question 11

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 12

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

Question 13

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 14

Farsightedness can be corrected with a converging lens.

Question 15

A diverging lens cannot be used as a magnifying glass.

Question 16

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

Question 17

A concave lens always produces a virtual image.

Question 18

The near point of a normal human eye is infinity.

Question 19

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

Question 20

A magnifying glass can be made from a diverging lens.

Question 21

The image formed by convex lenses are

A)always upright.
B)always real.
C)always virtual.
D)always inverted.
E)none of the above.

Question 22

A camera lens that covers the film with a field of view that corresponds approximately to that of normal vision is referred to as a

A)normal lens.
B)telephoto lens.
C)wide-angle lens.
D)zoom lens.
E)digital lens.

Question 23

A convex lens has a focal length f. An object is placed at f on the axis. The image formed is located

A)at infinity.
B)between 2f and infinity.
C)at 2f.
D)between f and 2f.
E)between the lens and f.

Question 24

An object is placed 100 cm in front of a lens of focal length 20 cm. A second lens is placed 35 cm beyond the first, this second lens having a focal length of 8.0 cm. The final image

A)is virtual and upright.
B)is real and upright.
C)is virtual and inverted.
D)is real and inverted.
E)cannot be determined with the information given.

Question 25

A convex lens has a focal length f. An object is placed between f and 2f on the axis. The image formed is located

A)at 2f.
B)between f and 2f.
C)at f.
D)between the lens and f.
E)at a distance greater than 2f from the lens.

Question 26

A light ray, traveling parallel to the axis of a thin concave lens, strikes the lens near its midpoint. After traveling though the lens, this ray emerges traveling obliquely to the axis of the lens

A)such that it never crosses the axis.
B)crossing the axis at a point equal to twice the focal length.
C)crossing the axis at a point equal to one-half the focal length.
D)passing between the lens and its focal point.
E)passing through the focal point.

Question 27

A convex lens has a focal length f. An object is placed between infinity and 2f from the lens on its axis. The image formed is located

A)at a distance greater than 2f from the lens.
B)at 2f.
C)between f and 2f.
D)at f.
E)between the lens and f.

Question 28

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 aperature.

Question 29

In calculating the lateral magnification from a lens, a negative result means

A)the image is larger than the object.
B)the image is smaller than the object.
C)the image is directed downward.
D)the image is inverted.
E)the calculation is incorrect.

Question 30

A camera lens that covers the film with a wider field of view than that of the eye and through which objects appear smaller is referred to as a

A)normal lens.
B)telephoto lens.
C)wide-angle lens.
D)zoom lens.
E)digital lens.

Question 31

Of the following lenses, which is not a converging lens?

A)concave meniscus
B)planoconcave
C)double convex
D)planoconvex
E)All of the above are not converging lenses.

Question 32

A lens of focal length 20 cm has an object of height 3.0 cm placed 100 cm in front of it. The image formed is

A)upright and smaller than the object.
B)inverted and smaller than the object.
C)inverted and larger than the object.
D)upright and larger than the object.
E)upright and the same size as the object.

Question 33

A light ray, traveling parallel to the axis of a convex thin lens, strikes the lens near its midpoint. After traveling through the lens, this ray emerges traveling obliquely to the axis of the lens

A)such that it never crosses the axis.
B)crossing the axis at a point equal to twice the focal length.
C)crossing the axis at a point equal to one-half the focal length.
D)passing between the lens and its focal point.
E)passing through its focal point.

Question 34

A convex lens has focal length f. An object is located at infinity. The image formed is located

A)at infinity.
B)at 2f.
C)between f and 2f.
D)at f.
E)between the lens and f.

Question 35

An object is placed 100 cm in front of a lens of focal length 20 cm. A second lens is placed 15 cm past the first lens. The second lens has a focal length of 40 cm. The final image

A)is real and upright.
B)is virtual and upright.
C)is real and inverted.
D)is virtual and inverted.
E)cannot be determined with the information given.

Question 36

Select which statement is correct in describing the image formed by a thin lens of a real object placed in front of the lens.

A)If the lens is convex, the image will never be virtual.
B)If the image is real, then it is also inverted.
C)If the image is real, then it is also upright.
D)If the image is virtual, then it is also inverted.

Question 37

A camera lens that acts like a telescope to magnify images is referred to as a

A)normal lens.
B)telephoto lens.
C)wide-angle lens.
D)zoom lens.
E)digital lens.

Question 38

A convex lens has focal length f. An object is placed at 2f on the axis. The image formed is located

A)between 2f and infinity.
B)at 2f.
C)between f and 2f.
D)at f.

Question 39

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 aperature.

Question 40

The images formed by concave lenses

A)are always real.
B)are always virtual.
C)could be real or virtual; it depends on whether the object distance is smaller or greater than the focal length.
D)could be real or virtual, but always real when the object is placed at the focal point.

Question 41

Consider the image formed by a refracting telescope. Suppose an opaque screen is placed in front of the lower half of the objective lens. What effect will this have?

A)The top half of the image will be blacked out.
B)The lower half of the image will be blacked out.
C)The entire image will be blacked out, since the entire lens is needed to form an image.
D)The image will appear as it would if the objective were not blocked, but it will be dimmer.
E)There will be no noticeable difference in the appearance of the image with the objective partially blocked or not.

Question 42

The image of the rare stamp you see through a magnifying glass is

A)always the same orientation as the stamp.
B)always upside-down compared to the stamp.
C)either the same orientation or upside-down, depending on how close the stamp is to the glass.
D)either the same orientation or upside-down, depending on the thickness of the glass used.
E)either the same orientation or upside-down, depending on the diameter of the glass used.

Question 43

What type of lens is a magnifying glass?

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

Question 44

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 45

If a person's eyeball is too long from front to back, the person is likely to suffer from

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

Question 46

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 47

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 48

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 49

Nearsightedness can usually be corrected with

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

Question 50

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 51

The principal refraction of light by the eye occurs at the

A)cornea.
B)lens.
C)retina.
D)iris.
E)optical nerve.

Question 52

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 53

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 54

Farsightedness can usually be corrected with

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

Question 55

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 56

An important reason for using a very large diameter objective in an astronomical telescope is

A)to increase the magnification.
B)to increase the resolution.
C)to form a virtual image, which is easier to look at.
D)to increase the width of the field of view.
E)to increase the depth of the field of view.

Question 57

If a person's eyeball is too short from front to back, the person is likely to suffer from

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

Question 58

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 59

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 60

The objectives of two astronomical telescopes have the same focal length but one objective has double the diameter of the other. An advantage of the telescope with the larger objective is

A)its higher power.
B)its greater aberration.
C)its higher price.
D)its brighter image.
E)its lower aberration.

Question 61

A person's eye lens is 2.7 cm away from the retina.
(a) 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?
(b) 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?

Question 62

A thin converging lens is found to form an image of a distant building 24 cm from the lens. If an object is placed 16 cm from the lens, how far from the object will the image be?

A)64 cm
B)72 cm
C)32 cm
D)96 cm
E)48 cm

Question 63

The focal lengths of the objective and the eyepiece of a microscope are 0.5 cm and 2.0 cm, respectively, and their separation adjusted for minimum eyestrain is 6.0 cm. The near-point distance of the person using the microscope is 25.0 cm.
(a) If the microscope is focused on a small object, what is the distance between the object and the objective lens?
(b) If the microscope is focused on a small object, what is its final magnification?

Question 64

An object is 12 cm in front of a converging lens with focal length 4 cm. Where is the image?

A)8.0 cm in front the lens
B)8.0 cm behind the lens
C)6.0 cm in front of the lens
D)6.0 cm behind the lens
E)4.0 cm in front of the lens

Question 65

An object is placed 21 cm from a concave lens of focal length 25 cm. What is the magnification?

A)-0.54
B)0.54
C)-0.32
D)-0.22
E)0.22

Question 66

An object, placed 12.0 cm from a lens, produces an image with a magnification of 5.0. What is the focal length of the lens?

A)24 cm
B)18 cm
C)60 cm
D)15 cm
E)9 cm

Question 67

A magnifying lens has a focal length of 10 cm. A person has a near point of 25 cm.
(a) What is the magnification of the lens for that person when their eyes are focused at infinity?
(b) What is the magnification of the lens for that person when their eyes are focused at their near point?

Question 68

An object is placed 60 cm from a convex lens of focal length 10 cm. What is the magnification?

A)-0.10
B)0.10
C)0.15
D)0.20
E)-0.20

Question 69

A lens of focal length 20 cm has an object of height 3.0 cm placed 100 cm in front of it. The image distance in this case is

A)33 cm.
B)20 cm.
C)25 cm.
D)17 cm.
E)-25 cm.

Question 70

You have available lenses of focal lengths 2.0 cm, 4.0 cm, 8.0 cm, and 16.0 cm.
(a) If you were to use any two of these lenses to build a telescope, what is the maximum magnification you could achieve?
(b) If you were to use any two of these lenses to build a telescope, what is the lens separation for the maximum magnification telescope?

Question 71

A person with normal eyesight uses a converging lens of focal length 10 cm. He holds the lens close to his eyes to finish an engraving job.
(a) What is the magnifying power of the lens?
(b) At what distance from the job he must hold the lens?

Question 72

The distance between the object 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. A person with a near point 25 cm is using the microscope.
(a) What is the largest angular magnification obtainable using the eyepiece alone as a magnifying lens?
(b) What is the total magnification of the microscope when used by the person of normal eyesight?

Question 73

An object is 80 cm in front of a lens. An image forms 10 cm behind the lens. The lateral magnification

A)is -8.
B)is -0.125.
C)is 8.
D)is 0.125.
E)cannot be determined with the information given.

Question 74

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 75

A person uses a converging lens of focal length 5.0 cm as a magnifying glass.
(a) What is the magnification if the person's eye is relaxed?
(b) What is the maximum possible magnification?

Question 76

It is desired to project an image of an object four times actual size with a lens of focal length 20 cm. What object distance should be used?

A)100 cm
B)80 cm
C)4 cm
D)25 cm
E)5 cm

Question 77

A 4.0 cm tall object is placed 60 cm away from a converging lens of focal length 30 cm. What is the nature and location of the image?

A)The image is real, 2.5 cm tall, 30 cm on the same side as object.
B)The image is virtual, 2.5 cm tall, 30 cm on the other side of the lens.
C)The image is virtual, 2.0 cm tall, 15 cm on the other side of the lens.
D)The image is virtual, 4.0 cm tall, 60 cm on the same side as object.
E)The image is real, 4.0 cm tall, 60 cm on the other side of the lens.

Question 78

An object is placed 10 cm from a convex lens of focal length 20 cm. What is the magnification?

A)0.50
B)1.0
C)1.5
D)2.0
E)2.5

Question 79

An object is placed 40 cm in front of a 20 cm focal length converging lens. How far is the image of this object from the lens?

A)40 cm
B)80 cm
C)20 cm
D)13 cm
E)none of the given answers

Question 80

An image is 4.0 mm in front of a converging lens with focal length 5.0 mm. Where is the object?

A)2.2 mm in front of the lens
B)2.2 mm behind the lens
C)9.0 mm in front of the lens
D)9.0 cm behind the lens
E)20 mm in front of the lens