Question 1

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?

Accepted Answer

(a) nearsighted (b) 14 cm

Question 2

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

Accepted Answer

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

Question 3

In a compound microscope

Accepted Answer

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. 
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. B

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?

Accepted Answer

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. 
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

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

Question 6

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

Accepted Answer

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. 
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.

Question 7

Farsightedness can usually be corrected with

Accepted Answer

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

Question 8

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

Accepted Answer

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

Question 9

A magnifying glass of focal length 150 mm is used to examine an old manuscript very
closely by a person with a near point at 25 cm.
(a) What is the maximum angular magnification given by the lens?
(b) What is the angular magnification for relaxed eye-viewing, with the image at infinity?

Accepted Answer

The answer of A magnifying glass of focal length 150...

Question 10

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

Accepted Answer

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. 
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 11

If the back of a person's eye is too close to the lens, this person is suffering from

Accepted Answer

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

Question 12

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?

Accepted Answer

A)  $0.50 \mathrm {~m}$ 
B)  $1.5 \mathrm {~m}$ 
C)  $0.60 \mathrm {~m}$ 
D)  $1.9 \mathrm {~m}$ 
E)  $0.75 \mathrm {~m}$ 
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 13

A camera with a 20-cm diameter lens is recording images using a filter that allows only
light of wavelength 600 nm to pass through.
(a) What is the limit on the angular resolution (in microradians) in this case?
(b) What is the diameter of the minimum-sized features that could be resolved on Mars
with this camera? The distance to Mars at the time is 9 $$9.0 \times 10 ^ { 7 } \mathrm {~km}$$

Accepted Answer

The answer of A camera with a 20-cm diameter lens...

Question 14

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?

Accepted Answer

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

Question 15

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

Accepted Answer

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

Question 16

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?

Accepted Answer

(a) 2.79 m

Question 17

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 $30 \mathrm {~cm}$ ?

Accepted Answer

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

Question 18

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?

Accepted Answer

(a) -75.0

Question 19

A simple compound microscope normally uses

Accepted Answer

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. 
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 20

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?

Accepted Answer

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

Exam 25: Optical Instruments

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?

In a compound microscope

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 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?

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

Farsightedness can usually be corrected with

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 magnifying glass of focal length 150 mm is used to examine an old manuscript very closely by a person with a near point at 25 cm. (a) What is the maximum angular magnification given by the lens? (b) What is the angular magnification for relaxed eye-viewing, with the image at infinity?

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

If the back of a person's eye is too close to the lens, this person is suffering from

What is the uncorrected near point of a farsighted person who can comfortably read a newspaper held 25 cm25 \mathrm {~cm}25 cm from his eyes when he wears +3.33+ 3.33+3.33 -diopter contact lenses?

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?

Without glasses, a person can comfortably read a magazine when it is held at 60 cm60 \mathrm {~cm}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 cm30 \mathrm {~cm}30 cm ?

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?

A simple compound microscope normally uses

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?

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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?

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 $30 \mathrm {~cm}$ ?