Deck 19: Optical Instruments

Question 1

A farsighted boy has a near point at 2.0 m and requires eyeglasses to correct his vision.Corrective lenses are available in increments in power of 0.25 diopters.The eyeglasses should have lenses of the lowest power for which the near point is no further than 25 cm.The boy borrows eyeglasses that have a power of + 2.75 diopters.With these eyeglasses,the near point of the boy,in cm,is closest to:

A)31
B)28
C)33
D)37
E)40

Answer 1

31

Question 2

A machinist with normal vision has a near point at 25 cm.The machinist wears eyeglasses in order to do close work.The power of the lenses is + 4.25 diopters.With these eyeglasses,the near point of the machinist,in cm,is closest to:

A)12
B)10
C)7
D)15
E)17

Answer 2

12

Question 3

Situation 19.2
The objective 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.The final image is viewed at infinity.The near point of the microscope user is at 25 cm.
In Situation 19.2,the overall magnification of the microscope is closest to:

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

Answer 3

300

Question 4

A lens of focal length 45 mm is used as a magnifier.The object being viewed is 6.8 mm long,and is positioned at the focal point of the lens.The lens is moved closer to the object,so that the image is now 25 cm from the lens.The distance the lens has been moved,in cm,is closest to:

A)0.69
B)0.76
C)0.62
D)0.55
E)0.48

Question 5

Situation 19.2
The objective 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.The final image is viewed at infinity.The near point of the microscope user is at 25 cm.
In Situation 19.2,the distance between the objective and the real image produced by it,in mm,is closest to:

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

Question 6

A lens of focal length 40 mm is mounted on a 35 mm camera.The lens aperture is set at f/5.6 and the shutter speed set at 1/250 s.A different camera has a lens of focal length 56 mm in place.The shutter speed is set at 1/60 s.The lens aperture setting,for the closest matching film exposure,is:

A)f/5.6
B)f/8
C)f/11
D)f/16
E)f/22

Question 7

Situation 19.2
The objective 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.The final image is viewed at infinity.The near point of the microscope user is at 25 cm.
In Situation 19.2,the distance between the object and the focal point of the objective,in mm,is closest to:

A)0.13
B)0.18
C)0.23
D)0.28
E)0.33

Question 8

The image of a tree on a 35 mm color slide is 1.7 mm high.It is to be projected onto a screen 8.0 m from the slide,and is to appear 559 mm high.(a)What focal length lens (in meters)is needed? (b)What is the distance in meters between the lens and the slide? (c)What is the magnification of the system?

A)(a)0.02 m (b)0.02 m
(c)329
B)(a)0.02 m (b)7.98 m
(c)0.00
C)(a)0.02 m (b)-0.02 m
(c)0.00
D)(a)0.02 m (b)-8.02 m
(c)0.00

Question 9

A lens of focal length 45 mm is mounted on a 35 mm camera.The lens aperture is set at f/ 2 and the shutter speed set at 1/2000 s.The aperture diameter,in mm,is closest to:

A)23
B)16
C)19
D)26
E)29

Question 10

Situation 19.1
The objective of a microscope has a focal length of 2.4 mm and the eyepiece has an angular magnification of 15.The object is positioned 0.06 mm beyond the focal point of the objective.The focal point of the eyepiece is positioned at the real image formed by the objective.
In Situation 19.1,the separation between the objective and the eyepiece,in mm,is closest to:

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

Question 11

A farsighted boy has a near point at 2.3 m and requires eyeglasses to correct his vision.Corrective lenses are available in increments in power of 0.25 diopters.The eyeglasses should have lenses of the lowest power for which the near point is no further than 25 cm.The correct choice of lens power for eyeglasses,in diopters,is:

A)+ 3.75
B)+ 3.50
C)+ 3.25
D)+ 4.00
E)+ 4.25

Question 12

In a 35 mm single lens reflex camera (SLR)the distance from the lens to the film is varied in order to focus on objects at varying distances.Over what range must a lens of 45 mm focal length vary if the camera is to be able to focus on objects ranging in distance from infinity down to 1.4 m from the camera?

A)1.49 mm
B)1.20 mm
C)4.48 mm
D)5.98 mm
E)2.09 mm

Question 13

A 35 mm camera equipped with a 45 mm focal length lens is used to photograph a tree 15 m tall.The aperture of the lens is set at f/ 2.The aperture diameter at f/ 2,in mm,is closest to:

A)23
B)14
C)18
D)27
E)31

Question 14

Situation 19.1
The objective of a microscope has a focal length of 2.4 mm and the eyepiece has an angular magnification of 15.The object is positioned 0.06 mm beyond the focal point of the objective.The focal point of the eyepiece is positioned at the real image formed by the objective.
In Situation 19.1,the overall magnification of the microscope is closest to:

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

Question 15

A simple camera lens with focal object length f_o = 3.00 cm perfectly focuses the image of an object on a photographic film located a distance 14.00 cm away from the lens.The object now moves away from the lens and the new focal distance is 13.00 cm. (a)How far did the object move? (b)What is the new magnification?

A)(a)0.08 cm (b)3.33
B)(a)0.03 cm (b)0.30
C)(a)990.00 cm (b)0.23
D)(a)12.22 cm (b)4.33

Question 16

A 35 mm camera equipped with a 40 mm focal length lens is used to photograph a tree 17 m tall.The aperture of the lens is set at f/8.A 32 mm high image of the tree on the film is required.The required distance,between the tree and the camera,to take the photograph is closest to:

A)21 m
B)22 m
C)23 m
D)24 m
E)26 m

Question 17

A lens of focal length 90 mm is used as a magnifier.The object being viewed is 9.9 mm long,and is positioned at the focal point of the lens.The angle subtended by the image at infinity,in milliradians,is closest to:

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

Question 18

Situation 19.3
The angular magnification of a refracting telescope is 40.When the object and final image are both at infinity,the distance between the eyepiece and the objective is 143.5 cm.The telescope is used to view a distant radio tower.The real image of the tower,formed by the objective,is 6.0 mm in height.The focal point of the eyepiece is positioned at the real image.
In Situation 19.3,the focal length of the objective,in cm,is closest to:

A)137
B)138
C)139
D)140
E)141

Question 19

A myopic girl wears eyeglasses that allow her to have clear distant vision.The power of the lenses of her eyeglasses is - 3.00 diopters.Without eyeglasses,the far point of the girl is closest to:

A)0.33 m
B)0.25 m
C)0.17 m
D)0.42 m
E)0.50 m

Question 20

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.The angular magnification of the magnifier is closest to:

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

Question 21

The objective lens of an astronomical telescope has a focal length of 60 cm and the eyepiece has a focal length of 2 cm.How far apart should the lenses be placed in order to form a final image at infinity?

A)44 cm
B)58 cm
C)76 cm
D)60 cm
E)62 cm

Question 22

A blue filter absorbs the blue light as white light passes through it.

Question 23

The objective and the eyepiece of a refracting astronomical telescope have focal lengths of 320 cm and 4.0 cm,respectively.The telescope is used to view Neptune and the final image is set at infinity.The diameter of Neptune is 4.96 $\times$ 10⁷ m and the distance from Earth at the time of observation is 4.4 $\times$ 10¹² m.The angle subtended by the final telescopic image of Neptune,in m rad,is closest to:

A)0.9
B)1.1
C)1.3
D)1.5
E)1.7

Question 24

If red light and violet light both strike and enter a sheet of glass at the same angle with respect to the normal,the violet light will be deflected from its original direction more than the red light will.

Question 25

Situation 19.3
The angular magnification of a refracting telescope is 40.When the object and final image are both at infinity,the distance between the eyepiece and the objective is 143.5 cm.The telescope is used to view a distant radio tower.The real image of the tower,formed by the objective,is 6.0 mm in height.The focal point of the eyepiece is positioned at the real image.
In Situation 19.3,the angle subtended by the final image of the tower is closest to:

A)0.15 rad
B)0.17 rad
C)0.19 rad
D)0.21 rad
E)0.23 rad

Question 26

To give large magnification,a telescope should have

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

Question 27

In a compound microscope

A)both the objective and the eyepiece form real images.
B)magnification is provided by the objective lens and not by the eyepiece.The eyepiece merely increases the resolution of the image viewed.
C)magnification is provided by the objective and not by the eyepiece.The eyepiece merely increases the brightness of the image viewed.
D)the magnification is m1 + M1,where m1 is the lateral magnification of the objective and M2 is the angular magnification of the eyepiece.
E)the image of the objective serves as the object for the eyepiece.

Question 28

What optical element would you need and how would you use it to determine the focal length of a concave lens.

Question 29

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 (near point at 25 cm).What is the angular magnification of the microscope?

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

Question 30

A nearsighted person requires glasses with diverging lens to read.

Question 31

The intensity of light decreases as the f-number of a camera lens is increased.

Question 32

You use a $600 lens from a photocopy machine hoping to make a good telescope.Yet the image is disappointingly bad.Why?

Question 33

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 for example such a person wanted to read a book at a distance of 25 cm,he would have to wear eyeglasses whose diopter power was approximately

A)+2.78 diopters.
B)+3.33 diopters.
C)-1.78 diopters.
D)+4.00 diopters.
E)-4.00 diopters.

Question 34

A magnifier consists of a converging lens with the object distance greater than the focal length of the lens.