Deck 23: Mirrors and Lenses

Question 1

The real image of an object is located 45.0 cm away from a concave mirror,which has a focal length of 10.0 cm.How far is the object from the mirror?

A)40.0 cm
B)35.0 cm
C)22.5 cm
D)12.9 cm

Answer 1

12.9 cm

Question 2

If a virtual image is formed along the principal axis 10 cm from a concave mirror with the focal length 15 cm,what is the object distance from the mirror?

A)30 cm
B)10 cm
C)12 cm
D)6.0 cm

Answer 2

6.0 cm

Question 3

How large should a wall-mounted mirror be to view the upper half of one's height,h?

A)h
B)h/2
C)h/4
D)The answer is not given.

Answer 3

h/4

Question 4

A convex mirror with focal length of -20 cm forms an image 12 cm behind the surface.Where is the object located as measured from the surface?

A)7.5 cm
B)15 cm
C)22 cm
D)30 cm

Question 5

Which best describes the image of a concave mirror when the object is located somewhere between the focal point and twice the focal point distance from the mirror?

A)virtual,upright and magnification greater than one
B)real,inverted and magnification less than one
C)virtual,upright and magnification less than one
D)real,inverted and magnification greater than one

Question 6

Which of the following best describes the image of a concave mirror when the object is at a distance greater than twice the focal point distance from the mirror?

A)virtual,upright and magnification greater than one
B)real,inverted and magnification less than one
C)virtual,upright and magnification less than one
D)real,inverted and magnification greater than one

Question 7

When the reflection of an object is seen in a plane mirror,the image is:

A)real and upright.
B)real and inverted.
C)virtual and upright.
D)virtual and inverted.

Question 8

Which of the following best describes the image from a plane mirror?

A)virtual and magnification greater than one
B)real and magnification less than one
C)virtual and magnification equal to one
D)real and magnification equal to one

Question 9

An object is held at a distance of 12 cm from a convex mirror creating an image that is 1/3 the object size.What is the focal length of the mirror?

A)-6.0 cm
B)-3.0 cm
C)-9.0 cm
D)-18 cm

Question 10

Which of the following best describes the image of a convex mirror when the object's distance from the mirror is less than the absolute value of the focal point distance?

A)virtual,upright and magnification greater than one
B)real,inverted and magnification less than one
C)virtual,upright and magnification less than one
D)real,inverted and magnification greater than one

Question 11

You stand two feet away from a plane mirror.How far is it from you to your image?

A)2.0 ft
B)3.0 ft
C)4.0 ft
D)5.0 ft

Question 12

A woman looking in a makeup mirror sees her face at twice its actual size and right-side up.If she is 28.0 cm from the mirror,what is its focal length?

A)18.6 cm
B)44.0 cm
C)48.3 cm
D)56.0 cm

Question 13

When the reflection of an object is seen in a plane mirror,the distance from the mirror to the image depends on:

A)the wavelength of light used for viewing.
B)the distance from the object to the mirror.
C)the distance of both the observer and the object to the mirror.
D)the size of the object.

Question 14

An object placed 12 cm from a concave mirror produces a real image 8.0 cm from the mirror.If the object is now moved to a new position 18.0 cm from the mirror,where is the new image located as measured from the mirror?

A)3.0 cm
B)6.5 cm
C)9.2 cm
D)14.6 cm

Question 15

If a man wishes to use a plane mirror on a wall to view both his head and his feet as he stands in front of the mirror,the required length of the mirror:

A)is equal to the height of the man.
B)is equal to one half the height of the man.
C)depends on the distance the man stands from the mirror.
D)depends on both the height of the man and the distance from the man to the mirror.

Question 16

A convex mirror with a focal length of -20 cm forms an image 15 cm behind the surface.If the object height is 1.2 cm what is the image height?

A)0.30 cm
B)0.75 cm
C)0.94 cm
D)3.0 cm

Question 17

The lateral magnification for a flat mirror:

A)is a function of the object distance.
B)is a function of the image distance.
C)is a function of the object and image distance.
D)is 1.

Question 18

If a virtual image is formed 10.0 cm along the principal axis from a convex mirror of focal length -15.0 cm,how far is the object from the mirror?

A)30.0 cm
B)10.0 cm
C)6.00 cm
D)3.00 cm

Question 19

A concave mirror forms a real image at 25.0 cm from the mirror surface along the principal axis.If the corresponding object is at a 10.0-cm distance,what is the mirror's focal length?

A)1.43 cm
B)16.7 cm
C)12.4 cm
D)7.14 cm

Question 20

Which of the following best describes the image of a concave mirror when the object's distance from the mirror is less than the focal point distance?

A)virtual,upright and magnification greater than one
B)real,inverted and magnification less than one
C)virtual,upright and magnification less than one
D)real,inverted and magnification greater than one

Question 21

When the reflection of an object is seen in a concave mirror the image will:

A)always be real.
B)always be virtual.
C)may be either real or virtual.
D)will always be enlarged.

Question 22

A glass block,for which n = 1.52,has a blemish located 3.2 cm from one surface.At what distance from that surface does the image of the blemish appear to the outside observer?

A)1.6 cm
B)2.1 cm
C)4.9 cm
D)6.4 cm

Question 23

A 3.0 cm tall object is placed along the principal axis of a thin convex lens of 30.0 cm focal length.If the object distance is 40.0 cm,which of the following best describes the image distance and height,respectively?

A)17.3 cm and 7.0 cm
B)120 cm and 9.0 cm
C)17.3 cm and 1.3 cm
D)120 cm and 1.0 cm

Question 24

If atmospheric refraction did not occur,how would the apparent time of sunrise and sunset be changed?

A)Both would be later.
B)Both would be earlier.
C)Sunrise would be later and sunset earlier.
D)Sunrise would be earlier and sunset later.

Question 25

Parallel rays of light that hit a concave mirror will come together:

A)at the center of curvature.
B)at the focal point.
C)at a point half way to the focal point.
D)at infinity.

Question 26

An object is placed 10 cm in front of a mirror,and an image is formed that has a magnification of 2.Which of the following statements is false?

A)The focal length of the mirror is 20 cm.
B)The image is virtual.
C)There is enough information to select the correct answer.
D)This is the only true statement.

Question 27

A container is filled with fluid 1,and the apparent depth of the fluid is 5.00 cm.The container is next filled with fluid 2,and the apparent depth of this fluid is 4.00 cm.If the index of refraction of the first fluid is 1.60,what is the index of refraction of the second fluid?

A)2.00
B)1.79
C)1.28
D)More information is needed to find the value.

Question 28

A container is filled with fluid 1 and the apparent depth of the fluid is 5 cm.The container is next filled with fluid 2,and the apparent depth of this fluid is 4 cm.What is the ratio of the indices of refraction of these fluids?

A)n1/n2 = 5/4
B)n1/n2 = 4/5
C)n1/n2 =
D)More information is needed to find the ratio.

Question 29

A girl is standing in front of a concave mirror.Consider two rays of light,one from her nose and one from her mouth that are parallel as they are traveling toward the mirror.These rays will come together:

A)at the focal point.
B)at the center of curvature.
C)at the image point.
D)behind the mirror if she is too close to the mirror.

Question 30

A candle is 49.0 cm in front of a convex spherical mirror of radius of curvature 70.0 cm.What are the image distance and the magnification,respectively?

A)-20.4 cm,+0.417
B)+20.4 cm,-0.417
C)+122.5 cm,+2.50
D)-20.4 cm,-0.417

Question 31

Ron fills a beaker with glycerin (n = 1.473)to a depth of 5.0 cm.If he looks straight down through the glycerin surface,he will perceive the liquid to be what apparent depth?

A)7.4 cm
B)5.0 cm
C)3.4 cm
D)1.0 cm

Question 32

A solid glass sphere with a radius of 5.00 cm and index of refraction of 1.52 has a small coin embedded 3.00 cm from the front surface of the sphere.For the viewer looking at the coin through the glass,at what distance from the front surface of the glass does the coin's image appear to be located?

A)2.48 cm
B)3.20 cm
C)5.00 cm
D)6.85 cm

Question 33

An object is placed 10 cm in front of a mirror,and an image is formed that has a magnification of 2.Which of the following statements is true?

A)The focal length of the mirror is 30 cm.
B)The image is real.
C)There is not enough information to select the correct answer.
D)This is the only true statement.

Question 34

An object of length 3.00 cm is inside a plastic block with index of refraction 1.40.If the object is viewed from directly above,what is the length of its image?

A)3.00 cm
B)4.20 cm
C)2.13 cm
D)0.467 cm

Question 35

An object 2 cm high is placed 10 cm in front of a mirror.What type of mirror and what radius of curvature is needed for an image that is upright and 4 cm tall?

A)Concave,R = 20 cm
B)Concave,R = 40 cm
C)Convex,R = -10 cm
D)Convex,R = -20 cm

Question 36

An object of length 3.00 cm is inside a plastic block with index of refraction 1.40.If the object is viewed through the top surface of the block at a non-zero angle from the normal,where is the object relative to its image?

A)in the same direction as its image
B)above the direction of its image
C)below the direction of its image
D)More information is needed.

Question 37

When the reflection of an object is seen in a convex mirror the image will:

A)always be real.
B)always be virtual.
C)may be either real or virtual.
D)will always be enlarged.

Question 38

Atmospheric refraction of light rays is responsible for:

A)spherical aberration.
B)mirages.
C)chromatic aberration.
D)light scattering.

Question 39

A goldfish is swimming in water (n = 1.33)inside a spherical plastic bowl of index of refraction 1.33.If the goldfish is 10 cm from the front wall of the 15-cm radius bowl,where does the goldfish appear to an observer in front of the bowl?

A)6.0 cm behind the plastic
B)7.0 cm behind the plastic
C)8.0 cm behind the plastic
D)9.0 cm behind the plastic

Question 40

An object is 12.0 cm from the surface of a spherical Christmas tree ornament that is 8.00 cm in diameter.What is the magnification of the image?

A)-0.200
B)-0.500
C)+0.143
D)+0.250

Question 41

Ansel places an object 30 cm from a thin convex lens along the axis.If a real image forms at a distance of 10 cm from the lens,what is the focal length of the lens?

A)30 cm
B)15 cm
C)10 cm
D)7.5 cm

Question 42

An object is placed at a distance of 50 cm from a thin lens along the axis.If a real image forms at a distance of 40 cm from the lens,on the opposite side from the object,what is the focal length of the lens?

A)22 cm
B)45 cm
C)90 cm
D)200 cm

Question 43

For a diverging lens with one flat surface,the radius of curvature for the curved surface is 20.0 cm.What must the index of refraction be so that the focal length is -15.0 cm?

A)0.333
B)1.33
C)2.33
D)5.00

Question 44

An object and a screen are separated by 20.00 cm.A convex lens is placed between them,5.00 cm from the object.In this position it causes a sharp image of the object to form on the screen.What is the focal length of the lens?

A)15.0 cm
B)5.00 cm
C)3.75 cm
D)2.00 cm

Question 45

An object,located 90 cm from a concave lens,forms an image 60 cm from the lens on the same side as the object.What is the focal length of the lens?

A)-36 cm
B)-75 cm
C)-180 cm
D)-150 cm

Question 46

Two thin lenses with focal lengths 25.0 cm and 30.0 cm are placed in contact in an orientation so that their optic axes coincide.What is the focal length of the two in combination? (Hint: A thin lens is one whose thickness is negligible).

A)13.6 cm
B)27.5 cm
C)55.0 cm
D)150 cm

Question 47

Two thin lenses with 10.0-cm focal lengths at are mounted at opposite ends of a 30.0-cm long tube.An object is located 45.0 cm from one end of the tube.How far from the opposite end is the final image?

A)12.8 cm
B)24.0 cm
C)25.6 cm
D)33.6 cm

Question 48

Ellen places an object 40.0 cm from a concave lens.If a virtual image appears 10.0 cm from the lens on the same side as the object,what is the focal length of the lens?

A)-50.0 cm
B)-13.3 cm
C)-10.0 cm
D)-8.00 cm

Question 49

A contact lens is made of plastic with an index of refraction 1.50.The lens has an outer radius of curvature of +2.0 cm and an innerradius of curvature of +2.5 cm.What is its focal length?

A)-20 cm
B)+6.7 cm
C)+10 cm
D)+20 cm

Question 50

Sally places an object 6.0 cm from a thin convex lens along its axis.The lens has a focal length of 9.0 cm.What are the respective values of the image distance and magnification?

A)-18 cm and 3.0
B)18 cm and 3.0
C)3.0 cm and -0.50
D)-18 cm and -3.0

Question 51

Two thin lenses,with focal lengths of 25.0 cm and -30.0 cm are placed in contact in an orientation so that their optic axes coincide.What is the focal length of the two in combination? {Hint: A thin lens is one whose thickness is negligible).

A)-5.0 cm
B)13.6 cm
C)55.5 cm
D)150 cm

Question 52

Two convex thin lenses with focal lengths 10.0 cm and 20.0 cm are aligned on a common axis,running left to right,the 10-cm lens being on the left.A distance of 20.0 cm separates the lenses.An object is located at a distance of 15.0 cm to the left of the 10-cm lens.Where will the final image appear as measured from the 20-cm lens?

A)-13.3 cm
B)-6.67 cm
C)+6.67 cm
D)+13.3 cm

Question 53

For a converging lens with two curved surfaces,the radius of curvature for both surfaces is 10 cm.If the focal length is 10 cm,what must the index of refraction be?

A)1.5
B)2.0
C)2.5
D)3.0

Question 54

A converging lens with two convex surfaces has a front surface with radius of curvature of 10.0 cm;the back surface has radius of curvature of 20.0 cm,and it is made from material with an index of refraction of 2.50.What is the focal length of the lens?

A)4.44 cm
B)13.3 cm
C)-13.3 cm
D)0.250 cm

Question 55

When an image is inverted compared to the object,it is also:

A)virtual.
B)reversed left to right.
C)enlarged.
D)diminished.

Question 56

What is the image distance of an object 1.00 m in front of a converging lens of focal length 20.0 cm?

A)+16.7 cm
B)+20.0 cm
C)+25.0 cm
D)+33.3 cm

Question 57

A projector lens is needed to form an image on a screen 10 times the size of its corresponding object.The screen is located 8.0 m from the lens.What is the required focal length of the lens?

A)0.32 m
B)0.54 m
C)0.73 m
D)1.25 m

Question 58

Which of the following best describes the image for a thin convex lens that forms whenever the object is at a distance less than one focal length from the lens?

A)inverted,enlarged and real
B)upright,enlarged and virtual
C)upright,diminished and virtual
D)inverted,diminished and real

Question 59

Which of the following best describes the image for a thin concave lens that forms whenever the magnitude of the object distance is less than that of the lens' focal length?

A)inverted,enlarged and real
B)upright,enlarged and virtual
C)upright,diminished and virtual
D)inverted,diminished and real

Question 60

An object is placed at a distance of 30 cm from a thin convex lens along its axis.The lens has a focal length of 10 cm.What are the values,respectively,of the image distance and magnification?

A)60 cm and 2.0
B)15 cm and 2.0
C)60 cm and -0.50
D)15 cm and -0.50

Question 61

Which of the following effects is the result of the fact that the index of refraction of glass will vary with wavelength?

A)spherical aberration
B)mirages
C)chromatic aberration
D)light scattering

Question 62

A fused combination of a diverging and converging lens pair each made from a different index of refraction glass,is used to reduce the occurrence of which of the following effects?

A)spherical aberration
B)mirages
C)chromatic aberration
D)light scattering

Question 63

A 100-cm focal length thin lens is placed in contact with one of 66.7 cm focal length.A 3.0 cm tall object is placed 50 cm in front of the combination.What is the size of the image?

A)3.8 cm
B)1.9 cm
C)4.0 cm
D)12 cm

Question 64

An eyeglass lens is cut with one surface having a radius R₁ and the other surface having a radius R₂,with R₁ < R₂.Both positive radii are measured from the same side with R₁ being the side closer to the eye.Is this convex-concave lens a converging lens or a diverging lens?

A)This is a converging lens.
B)This is a diverging lens.
C)This can be either a converging or diverging lens,as more information is needed for a final determination.
D)This is neither,since a lens cannot be made this way.

Question 65

A lens of 12.0-cm focal length is placed 20 cm to the right of the object and a mirror of focal length -20.0 cm is placed 50.0 cm to the right of the lens.Where is the final image formed?

A)15.0 cm to the left of the lens
B)17.1 cm to the left of the lens
C)10.0 cm to the right of the mirror
D)10.0 cm to the left of the mirror

Question 66

A real object is place a distance d from a converging lens.The object is then moved to a distance 2d from the converging lens.Which of the following statements is false?

A)The image in the first case with the object at distance d can be the larger one.
B)The image in the second case with the object at distance 2d can be the larger one.
C)If both images are real,the image in the second case is smaller.
D)If the image in the first case is real,the image in the second case is upright.

Question 67

An object is placed 40.0 cm to the right of a concave mirror with focal length 24.0 cm and 10.0 cm to the left of a lens with focal length -20.0 cm.Where is the image formed by both the mirror and the lens?

A)6.67 cm to the right of the object
B)6.67 cm to the right of the lens
C)40.0 cm to the right of the lens
D)20.0 cm to the right of the lens

Question 68

A lens has a focal length of 60 cm in air.If this lens were immersed in water,what focal length would result? The index of refraction of the lens is 1.500 and that of water is 1.333.The focal length of a thin lens with index n₁ submerged in a liquid with index n₂ is given by the modified lens maker's formula: .

A)240 cm
B)68 cm
C)53 cm
D)15 cm

Question 69

A lens of 12.0-cm focal length is placed 20 cm to the right of the object and a mirror of focal length -20.0 cm is placed 50.0 cm to the right of the lens.Where is the image formed by the mirror?

A)40.0 cm to the right of the mirror
B)5.00 cm to the left of the mirror
C)17.1 cm to the left of the lens
D)10.0 cm to the right of the mirror

Question 70

An image is formed using a convex lens,the image being 15 cm past the lens.A second lens is placed 25 cm past the first lens and another image is formed,this time 10 cm past the second lens.Which of the following statements is always true?

A)Both of the lenses have positive focal lengths.
B)The first lens is diverging,and the second is converging.
C)The first lens is converging,and the second is diverging.
D)None of the above statements is true.

Question 71

Use of a parabolic mirror,instead of one made of a circular arc surface,can be used to reduce the occurrence of which of the following effects?

A)spherical aberration
B)mirages
C)chromatic aberration
D)light scattering

Question 72

In an ideal case rays coming from an object toward a lens or mirror should be reasonably close to the optic axis.To the extent that this condition is not completely met,which one of the following effects occurs?

A)spherical aberration
B)mirages
C)chromatic aberration
D)light scattering

Question 73

An image is formed using a convex lens,the image being 15 cm past the lens.A second lens is placed 25 cm past the first lens and another image is formed,this time 10 cm past the second lens.Which of the following statements is true?

A)The last image is inverted with regard to the original object.
B)The last image must be larger than the object.
C)The first image is virtual.
D)None of the above statements is true.

Question 74

An object is placed 25 cm to the left of a lens of focal length 20 cm.75 cm to the right of this lens is a plane mirror.Where does the final image form?

A)25 cm to the right of the mirror
B)25 cm to the left of the mirror
C)50 cm to the left of the lens
D)100 cm to the left of the lens

Question 75

A concave mirror with focal length 24.0 cm is placed 40.0 cm to the left of the object.A convex lens of focal length 12.0 cm is placed 40.0 cm to the right of the object.Where is the image formed by both the mirror and the lens?

A)20.0 cm to the right of the object
B)30.0 cm to the right of the lens
C)60.0 cm to the right of the object
D)12.0 cm to the right of the lens

Question 76

A 100-cm focal length thin lens is placed in contact with one of 66.7 cm focal length.An object is placed 50 cm in front of the combination.What is the image distance?

A)40 cm
B)-25 cm
C)67 cm
D)200 cm

Question 77

Reducing the lens aperture size is a scheme one can use to reduce the occurrence of which of the following effects?

A)spherical aberration
B)mirages
C)chromatic aberration
D)light scattering

Question 78

A thin lens has a focal length of 10.00 cm for red light.If the index of refraction for the lens material tends to decrease with increasing wavelength,what is the focal length of the lens for blue light?

A)also 10.00 cm
B)less that 10.00 cm
C)more than 10.00 cm
D)It depends on whether the lens is converging or diverging.

Question 79

Three thin lenses,each of focal length f,are placed in contact.What is the resulting focal length of the combination?

A)f
B)3f
C)f/3
D)3/f

Question 80

A concave mirror has radius R.When an object is located a distance 2R from the lens,which describes the image formed?

A)real,inverted,diminished
B)real,inverted,enlarged
C)virtual,upright,diminished
D)real,inverted,of equal size