Deck 25: Optical Instruments

Question 1

Choose the one alternative that best completes the statement or answers the question.
Which one of the following is a characteristic of a compound microscope?

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

Answer 1

A

Question 2

Choose the one alternative that best completes the statement or answers the question.
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 should have a large focal length and the eyepiece should have a small focal length.
C) The objective lens should have a large focal length, but it doesn't matter what the focal length of the eyepiece is.
D) The objective lens and eyepiece should both have large focal lengths.
E) The objective lens should have a small focal length and the eyepiece should have a large focal length.

Answer 2

B

Question 3

Choose the one alternative that best completes the statement or answers the question.
What type of lens is used to make a magnifying glass?

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

Answer 3

A

Question 4

Choose the one alternative that best completes the statement or answers the question.
Farsightedness can usually be corrected with

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

Question 5

Choose the one alternative that best completes the statement or answers the question.
You have a choice between two lenses of focal lengths fa and fb, where fb = 2fa, to use as the objective lens in building a compound microscope. If the magnification you obtain using lens a is
Ma, what will be the magnification when using lens b? A) $M b = M _ { a } / 4$
B) $M _ { b } = M _ { a } / 2$
C) $M _ { b } = 8 M _ { a }$
D) $M _ { b } = 4 M _ { a }$
E) $M _ { b } = 2 M _ { a }$

Question 6

Choose the one alternative that best completes the statement or answers the question.
Jack and Mary view the same microorganism through the same compound microscope. Mary's near point distance, NM, is twice as large as Jack's near point distance, NJ. If Mary sees the
Microorganism with magnification MM, with what magnification does Jack see it?

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

Question 7

Choose the one alternative that best completes the statement or answers the question.
If a camera lens lets in an amount of light $I$ when it is set to $f / 4$ , then how much light will it let in when it is set to $f / 8$ ?

A) $I / 4$
B) $4 I$
C) $16 I$
D) $I / 2$
E) $2 I$

Question 8

Choose the one alternative that best completes the statement or answers the question.
Nearsightedness is usually corrected with

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

Question 9

Choose the one alternative that best completes the statement or answers the question.
If a camera lens aperture is set to $f / 4$ , then

A) the radius of the lens aperture is $1 / 4$ the focal length.
B) the radius of the lens aperture is 4 times its focal length.
C) the focal length of the lens is $4 \mathrm {~mm}$ .
D) the diameter of the lens aperture is 4 times its focal length.
E) the diameter of the lens aperture is $1 / 4$ the focal length.

Question 10

Choose the one alternative that best completes the statement or answers the question.
A simple compound microscope normally uses

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

Question 11

Choose the one alternative that best completes the statement or answers the question.
Which one of the following statements is correct?

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

Question 12

Choose the one alternative that best completes the statement or answers the question.
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 13

Choose the one alternative that best completes the statement or answers the question.
For relaxed viewing with a microscope or a telescope, the eyepiece is adjusted to place the image at

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

Question 14

Choose the one alternative that best completes the statement or answers the question.
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 B, because it has the longer focal length.
B) Lens A, because it has the shorter 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 15

Choose the one alternative that best completes the statement or answers the question.
The angular magnification of a magnifying glass is largest when the image is at

A) infinity.
B) the far point of the eye.
C) the near point of the eye.
D) the focal point of the lens.
E) The magnification depends on the magnifying glass lens, not where the person puts his eye.

Question 16

Choose the one alternative that best completes the statement or answers the question.
If the lens in a person's eye is too highly curved, this person is suffering from

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

Question 17

Choose the one alternative that best completes the statement or answers the question.
If the back of a person's eye is too close to the lens, this person is suffering from

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

Question 18

Choose the one alternative that best completes the statement or answers the question.
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) towards the CCD sensors
C) sideways from the CCD sensors
D) away from the CCD sensors

Question 19

Choose the one alternative that best completes the statement or answers the question.
In a compound microscope

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

Question 20

Choose the one alternative that best completes the statement or answers the question.
The closest object that a typical young person with normal vision can focus on clearly is closest to

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

Question 21

Write the word or phrase that best completes each statement or answers the question.
A zoom lens for a camera is adjusted to change its focal length from 38 mm to 304 mm. If
the same amount of light is to be admitted to the lens in both cases, what is the final
f-number if the original f-number was f/2.0?

Question 22

Choose the one alternative that best completes the statement or answers the question.
A 35-mm camera equipped with a 45-mm focal length lens is used to photograph a tree 15 m tall. If the aperture of the lens is set at f/2, what is the aperture diameter?

A) 23 mm
B) 27 mm
C) 32 mm
D) 18 mm
E) 14 mm

Question 23

Choose the one alternative that best completes the statement or answers the question.
Light of wavelength 500 nm illuminates a round 0.50-mm-diameter hole. A screen is placed 6.0 m past the slit. What is the width of the central bright circle on the screen? A) $3700 \mu \mathrm { m }$
B) $7.3 \mathrm {~mm}$
C) $260 \mu \mathrm { m }$
D) $15 \mathrm {~mm}$

Question 24

Choose the one alternative that best completes the statement or answers the question.
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) $M / 2$
B) $2 M$
C) $M / 4$
D) $M$
E) $4 M$

Question 25

Choose the one alternative that best completes the statement or answers the question.
A simple digital camera lens with focal length $f _ { O } = 3.00 \mathrm {~cm}$ perfectly focuses the image of an object on a CCD sensor located a distance $14.00 \mathrm {~cm}$ away from the lens. The object now moves away from the lens and the new distance between the lens and sensor is $13.00 \mathrm {~cm}$ .
(a) By what amount did the object change its distance from the lens?
(b) What is the new magnification?

A) (a) $0.08 \mathrm {~cm}$
(b) $3.33$
B) (a) $0.03 \mathrm {~cm}$
(b) $0.30$
C) (a) $12.22 \mathrm {~cm}$
(b) $4.33$
D) (a) $990.00 \mathrm {~cm}$
(b) $0.23$

Question 26

Choose the one alternative that best completes the statement or answers the question.
If a metal sheet containing a tiny hole is heated (without damaging it) and therefore expands, what happens to the angular location of the first-order diffraction maximum?

A) It doesn't change.
B) It moves toward the centerline.
C) It moves away from the centerline.

Question 27

Choose the one alternative that best completes the statement or answers the question.
A simple refracting telescope provides large magnification by employing

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

Question 28

Choose the one alternative that best completes the statement or answers the question.
A camera lens has a focal length of 50.0 mm and an aperture setting of f/4.00. What is the diameter of the aperture of this lens?

A) 200 mm
B) 12.5 mm
C) 25.0 mm
D) 35.4 mm
E) 10.1 mm

Question 29

Choose the one alternative that best completes the statement or answers the question.
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) $0.3 \mathrm {~mm}$
B) $0.5 \mathrm {~mm}$
C) $0.4 \mathrm {~mm}$
D) $0.2 \mathrm {~mm}$
E) $0.7 \mathrm {~mm}$

Question 30

Choose the one alternative that best completes the statement or answers the question.
The focal length of a camera lens is 40 mm and its aperture diameter is 10 mm. What is the f-number of this lens?

A) 0.25
B) 4.0
C) 0.40
D) 2.0
E) 5.6

Question 31

Choose the one alternative that best completes the statement or answers the question.
Light from a He-Ne laser of wavelength 633 nm passes through a circular aperture. The resulting pattern is observed on a screen 4.0 m behind the aperture, where the width of the central bright
Circle is 1.1 cm. What is the diameter of the hole? A) $4700 \mu \mathrm { m }$
B) $32,000 \mu \mathrm { m }$
C) $9.8 \mu \mathrm { m }$
D) $560 \mu \mathrm { m }$

Question 32

Write the word or phrase that best completes each statement or answers the question.
A 35-mm digital camera using a standard 50.0 mm lens is focused on a 1.80 m tall person
who is standing 3.25 m from the lens. You now refocus the camera on a 15.0 cm tall flower
that is 75.0 cm from the lens.
(a) In refocusing, by how much did you move the lens? Did you move it toward the film
or away from it?
(b) What is the height of the flower's image on the CCD sensor?

Question 33

Choose the one alternative that best completes the statement or answers the question.
Which one of the following is normally not a characteristic of a simple two-lens refracting astronomical telescope?

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

Question 34

Choose the one alternative that best completes the statement or answers the question.
Given perfect lenses, what is the main reason that a telescope with a large-diameter objective lens can produce a sharper image than one with a small-diameter lens?

A) A larger lens can focus more wavelengths of light than a smaller lens.
B) A larger lens has a longer focal length than a smaller lens.
C) A larger lens can focus more accurately than a smaller lens.
D) A larger lens can gather more light than a smaller lens.
E) There is less diffraction with a larger lens than with a smaller lens.

Question 35

Write the word or phrase that best completes each statement or answers the question.
A $35 - \mathrm { mm }$ single lens reflex (SLR) digital camera is using a lens of focal length $35.0 \mathrm {~mm}$ to photograph a person who is $1.80 \mathrm {~m}$ tall and located $3.60 \mathrm {~m}$ from the lens.
(a) How far is the CCD sensor from the lens when the person is in focus?
(b) How tall is the person's image on the CCD sensor?

Question 36

Write the word or phrase that best completes each statement or answers the question.
A slide projector needs to focus the image of a 24.0-mm × 36.0-mm slide onto a square
screen 1.50 m on each side. You want to fill the screen as completely as possible without
any of the image falling beyond the screen. Due to space constraints in the projector, the
slide must be placed 10.5 cm from the lens.
(a) What magnification does the projector produce?
(b) How far from the lens should the screen be placed?
(c) What focal length projector lens is needed?

Question 37

Choose the one alternative that best completes the statement or answers the question.
A round 0.85-mm-diameter hole is illuminated by infrared light of wavelength 2.5 µm What is the angle of the first dark fringe in the resulting pattern? A) $4.8 \times 10 ^ { - 2 }$ degrees
B) $0.21$ degrees
C) $1.2 \times 10 ^ { - 2 }$ degrees
D) $3.6 \times 10 ^ { - 3 }$ degrees

Question 38

Choose the one alternative that best completes the statement or answers the question.
You have a choice between two lenses of focal lengths fa and fb, where fb = 2fa, to use as the objective lens in building a refracting telescope. If the magnification you obtain using lens a is Ma,
What will be the magnification when using lens b? A) $M _ { b } = M _ { a } / 4$
B) $M _ { b } = 2 M _ { a }$
C) $M b = 8 M _ { a }$
D) $M _ { b } = 4 M _ { a }$
E) $M _ { b } = M _ { a } / 2$

Question 39

Choose the one alternative that best completes the statement or answers the question.
A $35 - \mathrm { mm }$ camera equipped with a $40 - \mathrm { mm }$ focal length lens is used to photograph a tree $17 \mathrm {~m}$ 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) $22 \mathrm {~m}$
B) $26 \mathrm {~m}$
C) $21 \mathrm {~m}$
D) $23 \mathrm {~m}$
E) $24 \mathrm {~m}$

Question 40

Choose the one alternative that best completes the statement or answers the question.
A lens of focal length $45 \mathrm {~mm}$ is mounted on a $35 - \mathrm { mm }$ camera. The lens aperture is set at $f / 2.0$ and the shutter speed set at $1 / 2000 \mathrm {~s}$ . The photographer wants to keep the same exposure (amount of light), but wants to change the $f$ -number to $f / 8.0$ for greater depth of field. What should be the new shutter speed to maintain the same exposure? A) $1 / 8000 \mathrm {~s}$
B) $1 / 1000 \mathrm {~s}$
C) $1 / 4000 \mathrm {~s}$
D) $1 / 125 \mathrm {~s}$
E) $1 / 500 \mathrm {~s}$

Question 41

Write the word or phrase that best completes each statement or answers the question.
A nearsighted man wears contact lenses of -3.00 diopters. With these lenses, his corrected
near point is 25.0 cm. What is his uncorrected near point?

Question 42

Write the word or phrase that best completes each statement or answers the question.
A person's hyperopic (farsighted) eye can focus on objects that are 75 cm away and
farther. What power and what focal length contact lenses should be prescribed so this
person can see objects 25 cm and farther from the eye?

Question 43

Choose the one alternative that best completes the statement or answers the question.
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) 2.4 cm
B) -2.4 cm
C) 2.6 cm
D) 3.4 cm
E) -3.4 cm

Question 44

Choose the one alternative that best completes the statement or answers the question.
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) +60 cm
D) +30 cm
E) +130 cm

Question 45

Choose the one alternative that best completes the statement or answers the question.
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) 40 cm
B) 28 cm
C) 37 cm
D) 31 cm
E) 33 cm

Question 46

Choose the one alternative that best completes the statement or answers the question.
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) -1.78 diopters
B) +3.33 diopters
C) -4.00 diopters
D) +4.00 diopters
E) +2.78 diopters

Question 47

Write the word or phrase that best completes each statement or answers the question.
For an eye that is 2.4 cm in diameter, what must be the range of focal lengths of the lens to
focus objects from the near point (25 cm) to infinity on the retina?

Question 48

Choose the one alternative that best completes the statement or answers the question.
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) 15 cm
B) 7 cm
C) 17 cm
D) 10 cm
E) 12 cm

Question 49

Choose the one alternative that best completes the statement or answers the question.
What is the power of a lens that has a focal length of -40 cm and a width of 2.0 cm?

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

Question 50

Choose the one alternative that best completes the statement or answers the question.
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) 0.25 m
B) 0.42 m
C) 0.17 m
D) 0.50 m
E) 0.33 m

Question 51

Choose the one alternative that best completes the statement or answers the question.
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) 2.2 cm
D) -2.4 cm
E) 2.4 cm

Question 52

Write the word or phrase that best completes each statement or answers the question.
A nearsighted person has a near point of 12 cm and a far point of 17 cm. If the corrective
lens is 2.0 cm from his eye, (a) what lens power will enable this person to see distant
objects clearly, and (b) what then will be the new near point of his eye?

Question 53

Choose the one alternative that best completes the statement or answers the question.
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) -2.4 diopters
B) +4.2 diopters
C) -4.2 diopters
D) +2.5 diopters
E) -2.5 diopters

Question 54

Write the word or phrase that best completes each statement or answers the question.
A person uses corrective glasses of power -8.5 D that are worn 2.0 cm from her eye.
(a) Is she nearsighted or farsighted?
(b) What is her far point without glasses?

Question 55

Write the word or phrase that best completes each statement or answers the question.
A person is nearsighted with a far point of 75.0 cm.
(a) What focal length contact lens is needed to give him normal vision?
(b) What is the power of the corrective lens?

Question 56

Choose the one alternative that best completes the statement or answers the question.
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) 10 cm
B) 25 cm
C) 55 cm
D) 2.5 cm
E) 0.25 cm

Question 57

Write the word or phrase that best completes each statement or answers the question.
What power (in diopters) of corrective contact lens is required to correct the vision of a
myopic eye whose far point is at 170 cm?

Question 58

Write the word or phrase that best completes each statement or answers the question.
A nearsighted person has a far point of 50 cm for his right eye and 150 cm for his left eye.
For each eye, what power contact lens will allow the person to see gorgeous sunsets?

Question 59

Choose the one alternative that best completes the statement or answers the question.
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) +3.6 diopters
B) +0.28 diopters
C) -0.28 diopters
D) +1.8 diopters
E) -3.6 diopters

Question 60

Choose the one alternative that best completes the statement or answers the question.
What is the power of the lens that has a focal length of 40 cm and a diameter if 5.0 cm?

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

Question 61

Choose the one alternative that best completes the statement or answers the question.
What power contact lens must be used to correct the vision of a nearsighted person whose far point is 40 cm?

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

Question 62

Choose the one alternative that best completes the statement or answers the question.
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 63

Choose the one alternative that best completes the statement or answers the question.
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) 10.2 cm
B) -100 cm
C) 31.3 cm
D) 20.8 cm
E) -31.3 cm

Question 64

Choose the one alternative that best completes the statement or answers the question.
What is the uncorrected near point of a farsighted person who can comfortably read a newspaper held $25 \mathrm {~cm}$ from his eyes when he wears $+ 3.33$ -diopter contact lenses?

A) $0.50 \mathrm {~m}$
B) $1.5 \mathrm {~m}$
C) $0.60 \mathrm {~m}$
D) $1.9 \mathrm {~m}$
E) $0.75 \mathrm {~m}$

Question 65

Choose the one alternative that best completes the statement or answers the question.
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) $- 80 \mathrm {~cm} , - 1.3$ diopters
B) $- 1.3 \mathrm {~cm} , + 1.3$ diopters
C) $+ 80 \mathrm {~cm} , - 1.3$ diopters
D) $+ 80 \mathrm {~cm}$ , $+ 1.3$ diopters
E) $- 80 \mathrm {~cm} , + 1.3$ diopters

Question 66

Choose the one alternative that best completes the statement or answers the question.
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) +4.2 diopters
C) -4.0 diopters
D) +2.8 diopters
E) -4.2 diopters

Question 67

Choose the one alternative that best completes the statement or answers the question.
Without glasses, a person can comfortably read a magazine when it is held at $60 \mathrm {~cm}$ 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 $30 \mathrm {~cm}$ ?

A) $+ 60 \mathrm {~cm}$
B) $- 30 \mathrm {~cm}$
C) $+ 90 \mathrm {~cm}$
D) $+ 30 \mathrm {~cm}$
E) $- 60 \mathrm {~cm}$

Question 68

Choose the one alternative that best completes the statement or answers the question.
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) +2.2 diopters
B) -1.1 diopters
C) -2.2 diopters
D) +1.1 diopters
E) -1.7 diopters

Question 69

Choose the one alternative that best completes the statement or answers the question.
What power contact lens is needed to correct for farsightedness where the uncorrected near point is 75 cm? A) $- 2.7 \mathrm { D }$
B) $- 5.3 D$
C) $+ 2.7 \mathrm { D }$
D) $+ 5.3$ D

Question 70

Choose the one alternative that best completes the statement or answers the question.
A nearsighted person wears contact lenses having a power of -0.15 diopters. What is the person's uncorrected far point?

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

Question 71

Choose the one alternative that best completes the statement or answers the question.
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) -0.24 diopters
B) 0.48 diopters
C) -0.48 diopters
D) 0.24 diopters
E) -0.36 diopters

Question 72

Choose the one alternative that best completes the statement or answers the question.
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) $+ 36.4 \mathrm {~cm}$
B) $+ 32.5 \mathrm {~cm}$
C) $+ 21.2 \mathrm {~cm}$
D) $- 21.2 \mathrm {~cm}$
E) $- 36.4 \mathrm {~cm}$

Question 73

Choose the one alternative that best completes the statement or answers the question.
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) $+ 3.2$ diopters
B) $+ 3.0$ diopters
C) $- 2.0$ diopters
D) +2.5 diopters

Question 74

Choose the one alternative that best completes the statement or answers the question.
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) $+ 0.056$ diopters
B) $- 0.056$ diopters
C) $- 5.6$ diopters
D) $+ 5.6$ diopters

Question 75

Choose the one alternative that best completes the statement or answers the question.
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) $6.0 \mathrm {~cm}$
B) $5.0 \mathrm {~cm}$
C) $2.0 \mathrm {~cm}$
D) $3.0 \mathrm {~cm}$
E) $4.0 \mathrm {~cm}$

Question 76

Choose the one alternative that best completes the statement or answers the question.
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) $5.7$
E) $4.7$

Question 77

Choose the one alternative that best completes the statement or answers the question.
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) $- 4.72$ diopters
B) $+ 7.00$ diopters
C) $- 2.75$ diopters
D) $+ 4.72$ diopters
E) $+ 2.75$ diopters

Question 78

Choose the one alternative that best completes the statement or answers the question.
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) -5.2 m
C) -4.8 m
D) 4.2 m
E) 5.2 m

Question 79

Choose the one alternative that best completes the statement or answers the question.
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) +110 cm
C) +50 cm
D) -110 cm
E) -30 cm

Question 80

Choose the one alternative that best completes the statement or answers the question.
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) $- 42.9 \mathrm {~cm} , + 2.33$ diopters
B) $- 42.9 \mathrm {~cm} , - 2.33$ diopters
C) $+ 42.9 \mathrm {~cm} , + 2.33$ diopters
D) $+ 60 \mathrm {~cm} , + 42.9$ diopters
E) $+ 42.9 \mathrm {~cm} , - 2.33$ diopters