Question 1

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

Accepted Answer

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

Question 2

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 3

The eyepiece of a compound microscope has a focal length of 2.50 cm,and the objective has a focal length of 1.60 cm.The two lenses are separated by 14.0 cm.The microscope is used by a person with normal eyes,having a near point at 25 cm.What is the magnitude of the magnification of the microscope?

Accepted Answer

A) 72 
B) 88 
C) 180 
D) 219 
E) 115 
A) 72 
B) 88 
C) 180 
D) 219 
E) 115

Question 4

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?

Accepted Answer

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

Question 5

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?

Accepted Answer

A) -100 cm 
B) -31.3 cm 
C) 10.2 cm 
D) 20.8 cm 
E) 31.3 cm 
A) -100 cm 
B) -31.3 cm 
C) 10.2 cm 
D) 20.8 cm 
E) 31.3 cm

Question 6

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

Question 7

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

Accepted Answer

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

Question 8

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?

Accepted Answer

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

Question 9

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?

Accepted Answer

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

Question 10

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?

Accepted Answer

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

Question 11

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?

Accepted Answer

A) 1.7 
B) 2.7 
C) 3.7 
D) 4.7 
E) 5.7 
A) 1.7 
B) 2.7 
C) 3.7 
D) 4.7 
E) 5.7

Question 12

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?

Accepted Answer

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

Question 13

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?

Accepted Answer

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

Question 14

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 15

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 distance between the objective lens and the real image that it produces?

Accepted Answer

A) 116 mm 
B) 120 mm 
C) 124 mm 
D) 128 mm 
E) 132 mm 
A) 116 mm 
B) 120 mm 
C) 124 mm 
D) 128 mm 
E) 132 mm

Question 16

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?

Accepted Answer

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

Question 17

A simple compound microscope normally uses

Accepted Answer

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. 
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 18

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 19

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

Accepted Answer

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

Question 20

A simple refracting telescope provides large magnification by employing

Accepted Answer

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. 
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.

Exam 27: Optical Instruments

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

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

The eyepiece of a compound microscope has a focal length of 2.50 cm,and the objective has a focal length of 1.60 cm.The two lenses are separated by 14.0 cm.The microscope is used by a person with normal eyes,having a near point at 25 cm.What is the magnitude of the magnification of the microscope?

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

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 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 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?

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 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 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 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?

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 simple compound microscope normally uses

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

A simple refracting telescope provides large magnification by employing

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