Question 1

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

Accepted Answer

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

Question 2

The objective lens of a telescope has a focal length of 1.90 m. 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?

Accepted Answer

2.26 m

Question 3

You have available lenses of focal lengths 2.0 cm, 4.0 cm, 8.0 cm, and 16 cm. If you could use any two of these lenses to build a telescope, what is the lens separation for the telescope to provide the maximum magnification for comfortable viewing of a planet?

Accepted Answer

A)  10.0 cm 
B)  12.0 cm 
C)  18.0 cm 
D)  24.0 cm 
A)  10.0 cm 
B)  12.0 cm 
C)  18.0 cm 
D)  24.0 cm C

Question 4

What is the minimum distance between two points on the Moon that could be just resolved by the Keck telescope in Hawaii using a wavelength of 600 nm and having perfect optics? The diameter of this telescope mirror system is 10 m, and the distance to the Moon is 380,000 km.

Accepted Answer

The answer of What is the minimum distance between two...

Question 5

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?

Accepted Answer

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

Question 6

A telescope has an angular magnification of 250 when used with a 20 mm eyepiece. What is the focal length of the objective lens?

Accepted Answer

A)  5.0 cm 
B)  25 m 
C)  5000 cm 
D)  5.0 m 
E)  2.5 m 
A)  5.0 cm 
B)  25 m 
C)  5000 cm 
D)  5.0 m 
E)  2.5 m

Question 7

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

Accepted Answer

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

Question 8

A certain astronomical telescope has a diameter of 5.60 m. What is the minimum angle of resolution for this telescope when it is forming images using light of wavelength 620 nm?

Accepted Answer

A)  1.11 × 10-7 rad 
B)  3.11 × 10-7 rad 
C)  2.70 × 10-7 rad 
D)  1.35 × 10-7 rad 
E)  4.05 × 10-7 rad 
A)  1.11 × 10-7 rad 
B)  3.11 × 10-7 rad 
C)  2.70 × 10-7 rad 
D)  1.35 × 10-7 rad 
E)  4.05 × 10-7 rad

Question 9

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?

Accepted Answer

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

Question 10

An astronomical refracting telescope is made from two lenses. The objective lens has a focal length of $114 \mathrm {~cm} \text {, }$ and the eyepiece lens has a focal length of $17.0 \mathrm {~cm} .$ (a) What is the total length of the telescope? (b) What is the angular magnification of the telescope?
(c) What is the magnification by turning the telescope around and looking through the objective lens first?

Accepted Answer

A)  (a) 131 cm 
$\quad$(b) 6.71
$\quad$(c) 0.15 
B)  (a) 97 cm 
$\quad$(b) 0.15
$\quad$(c) 6.71 
C)  (a) 262 cm 
$\quad$(b) 0.87
$\quad$(c) 1.15 
D)  (a) 194 cm
$\quad$(b) 1.18
$\quad$(c) 0.85 
A)  (a) 131 cm 
$\quad$(b) 6.71
$\quad$(c) 0.15 
B)  (a) 97 cm 
$\quad$(b) 0.15
$\quad$(c) 6.71 
C)  (a) 262 cm 
$\quad$(b) 0.87
$\quad$(c) 1.15 
D)  (a) 194 cm
$\quad$(b) 1.18
$\quad$(c) 0.85

Question 11

The objective lens and the eyepiece of a microscope have focal lengths of 4.0 mm and 25 mm, respectively. The objective produces a real image 30 times the size of the object, with the final image viewed at infinity. The near point of the microscope user is at 25 cm. What is the magnitude of the overall magnification of the microscope?

Accepted Answer

A)  250 
B)  300 
C)  350 
D)  400 
E)  450 
A)  250 
B)  300 
C)  350 
D)  400 
E)  450

Question 12

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

Accepted Answer

The answer of A student wishing to build a telescope...

Question 13

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?

Accepted Answer

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

Question 14

Suppose your telescope has perfect mirrors and is limited only by diffraction. If you are viewing with light of 400 nm wavelength, what diameter mirror in a space telescope would have 1.0-km resolution of objects on Mars when viewed from above the earth at a time when the Earth-Mars distance of 80 million kilometers?

Accepted Answer

A)  39 km 
B)  3.9 m 
C)  3.9 km 
D)  39 m 
E)  390 m 
A)  39 km 
B)  3.9 m 
C)  3.9 km 
D)  39 m 
E)  390 m

Question 15

Astronomers are proud of their telescopes and often say they can "resolve a dime at so many miles." How many miles from a $\text { 102-cm-diameter }$ telescope mirror can you place a coin of diameter 3.0 cm and just resolve the coin using light of wavelength $389 \mathrm {~nm} ?$ (1 mi = 1.609 km)

Accepted Answer

A)  19 mi 
B)  9.7 mi 
C)  40 mi 
D)  190,000,000 mi 
A)  19 mi 
B)  9.7 mi 
C)  40 mi 
D)  190,000,000 mi

Question 16

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?

Accepted Answer

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

Question 17

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?

Accepted Answer

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

Question 18

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

Accepted Answer

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

Question 19

A 35-mm single lens reflex (SLR) digital camera is using a lens of focal length 35.0 mm to photograph a person who is 1.80 m tall and located 3.60 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?

Accepted Answer

(a) 3.53 c

Question 20

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

Accepted Answer

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. 
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.

Exam 19: Optical Instruments

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

The objective lens of a telescope has a focal length of 1.90 m. 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?

You have available lenses of focal lengths 2.0 cm, 4.0 cm, 8.0 cm, and 16 cm. If you could use any two of these lenses to build a telescope, what is the lens separation for the telescope to provide the maximum magnification for comfortable viewing of a planet?

What is the minimum distance between two points on the Moon that could be just resolved by the Keck telescope in Hawaii using a wavelength of 600 nm and having perfect optics? The diameter of this telescope mirror system is 10 m, and the distance to the Moon is 380,000 km.

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 telescope has an angular magnification of 250 when used with a 20 mm eyepiece. What is the focal length of the objective lens?

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

A certain astronomical telescope has a diameter of 5.60 m. What is the minimum angle of resolution for this telescope when it is forming images using light of wavelength 620 nm?

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

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 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?

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?

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

A 35-mm single lens reflex (SLR) digital camera is using a lens of focal length 35.0 mm to photograph a person who is 1.80 m tall and located 3.60 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?

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

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