Deck 21: Geometric Optics

Question 1

An object 6 cm in front of a concave mirror has a height of 2 cm. The mirror has a radius of curvature of 6 cm. What is the image height and position?

A)The image is 6 cm on the other side of the mirror, and 2 times bigger.
B)The image is 6 cm on the same side of the mirror, and the same size as the object.
C)The image is 3 cm on the other side of the mirror, and 2 times bigger.
D)The image is 3 cm on the same side of the mirror, and the same size as the object.

Answer 1

The image is 6 cm on the same side of the mirror, and the same size as the object.

Question 2

You observe a reflection on a flat vertical mirror. What is the change of the angle of a reflected ray if you rest the mirror on a wall leaning it at an angle of 30° with respect to vertical direction?

A)60°
B)30°
C)15°
D)0°

Answer 2

60°

Question 3

An object 6 cm in front of a concave mirror has a height of 2 cm. The mirror has a radius of curvature of 12 cm. What is the image height and position?

A)The image is 6 cm on the other side of the mirror, and 2 times bigger.
B)The image is 6 cm on the same side of the mirror, and the same size as the object.
C)The image is in infinity on the other side of the mirror, and is much bigger.
D)The image is in infinity on the same side of the mirror, and is the same size as the object.

Answer 3

The image is in infinity on the same side of the mirror, and is the same size as the object.

Question 4

A compound microscope has an objective with a focal length of 3.0 mm and an eyepiece with a focal length of 3.50 cm. The object is placed 3.8 mm from the objective. What is the magnification of the microscope?

A)-27
B)+27
C)-7
D)+7

Question 5

An object 5 cm high is located at a distance of 5 cm in front of a converging lens. The focal length is 10 cm. What is the size of the image, and is it inverted or upright?

A)10 cm, upright
B)10 cm, inverted
C)3.3 cm, upright
D)3.3 cm, inverted

Question 6

Which of the following describes the image formed in a plane mirror?

A)It is always real.
B)It is always virtual.
C)It is either real or virtual, depending on the type of the mirror.
D)It is either real or virtual, depending on which side of the mirror it is formed.

Question 7

If an object is placed at the centre of the curvature of a concave mirror, which of the following describes the image?

A)in the centre of the curvature and the same size as the object
B)in the centre of the curvature and smaller than the object
C)in the focus and the same size as the object
D)in the focus and larger than the object

Question 8

Which of these statements describes a specular angle?

A)the angle between a reflected ray and the surface of a mirror at a point where an incident ray strikes the mirror
B)the angle between a reflected ray and a normal to the surface of a mirror at a point where the incident ray strikes the mirror
C)the angle between a reflected ray and an incident ray at a point where the incident ray strikes a mirror
D)the angle between an incident ray and the surface of a mirror at a point where the incident ray strikes the mirror

Question 9

A dentist is using concave mirror. The focal length is 2 cm. If the dentist holds the mirror 0.5 cm away from the tooth, how much is the tooth magnified and is it inverted or upright?

A)3 times, inverted
B)3 times, upright
C)4/3 times, inverted
D)4/3 times, upright

Question 10

Which of the following equations is the correct version of Snell's law?

A)n₁/n₂ = sin(á₁)/sin(á₂)
B)n₁/n₂ = ë₁/ë₂
C)n₁/n₂ = v₁/v₂
D)n₁/n₂ = ë₂/ë₁

Question 11

What is the relationship between incident and reflected angles?

A)The reflected angle is equal to the incident angle.
B)The reflected angle is larger than the incident angle.
C)The reflected angle is smaller than the incident angle.
D)It depends on the type of reflection.

Question 12

The light is incident on the interface between media with two indices of refraction such that n₁ < n₂, and refracts. What is the relationship between the frequency of the light in the two media, f₁ and f₂?

A)f₁ < f₂
B)f₁ = f₂
C)f₁ > f₂
D)We need to know other information to answer.

Question 13

An object 5 cm high is located in front of a converging lens at a distance of 20 cm. The focal length is 10 cm. What is the size of the image, and is it inverted or upright?

A)5 cm, upright
B)5 cm, inverted
C)1.7 cm, upright
D)1.7 cm, inverted

Question 14

Which of these statements describes how the refractive power of the interface between two media is represented?

A)as the difference of indices of refraction of the two media
B)as the ratio of indices of refraction of the two media
C)as the difference of indices of refraction of the two media divided by the radius of curvature
D)as the ratio of indices of refraction of the two media divided by the radius of curvature

Question 15

You are looking at your face at a distance of 20 cm in front of a concave mirror with a focal length of 30 cm. What is the size of the image of your face compared to its real size?

A)half as large
B)1.5 times larger
C)2 times larger
D)3 times larger

Question 16

Which of the following describes the image formed in a plane mirror?

A)It is inverted and on the same side of the mirror.
B)It is upright and on the same side of the mirror.
C)It is upright and on the opposite side of the mirror.
D)It is inverted and on the opposite side of the mirror.

Question 17

Which of the following describes the image from a convex mirror?

A)It can be larger than the object.
B)It can be smaller than the object.
C)It can be real.
D)It can be inverted.

Question 18

You are looking at your face at a distance of 30 cm in front of a concave mirror with a focal length of 20 cm. What is the size of the image of your face compared to its real size?

A)half as large
B)1.5 times larger
C)2 times larger
D)3 times larger

Question 19

Which of these statements describes spherical aberration?

A)absence of a focal point only in spherical mirrors
B)absence of a focal point only in spherical lenses
C)absence of a focal point only in parabolic mirrors
D)absence of a focal point in spherical mirrors and lenses

Question 20

Due to hyperopia, a person has a near point at 60 cm. What is the refractive power of the glasses prescribed to correct the sight?

A)-2.3 dpt
B)+2.3 dpt
C)-5.7 dpt
D)+5.7 dpt

Question 21

A compound microscope has an objective with a focal length of 2.5 mm and an eyepiece with a focal length of 3.0 cm. If the magnification of the microscope is 68, how far from the objective is the object placed?

Question 22

The ray model of light is applicable when the objects are not smaller than the wavelength of the light with which we observe them.

Question 23

Newton developed the wave model of light.

Question 24

When a light ray is incident on a convex mirror, with the direction parallel to the optical axis, in which direction is the beam reflected?

Question 25

A specular angle is the reflected angle of a light ray that is measured from the normal to the surface of a mirror.

Question 26

The refractive power of a thin lens is an inverse of its radius of curvature.

Question 27

The diopter unit corresponds to the SI unit metre.

Question 28

A fish is looking from the water out to the air. At what angle with the normal to the water's surface does the fish need to look in order to spot a boat on the surface of the water? Indices of refraction are, for air and water, n_air = 1 and n_water = 1.33.

Question 29

Suppose you look at a bacterium through a compound microscope with magnification of 600. Could you see a bacterium with a length of 2 ìm? The eye can resolve 2 × 10^-4 radians.

Question 30

Figure 21.2 The figure shows a cross-sectional of a human eye: (1) lens, (2) anterior chamber, (3) cornea, (4) iris, (5) vitreous body, (6) ciliary muscle, (7) retina, (8) fovea centralis, and (9) optic nerve. (10) indicates the blind spot, which is due to the optic nerve passing through the retina to the brain.
Describe the path of light entering the eye from a distant object (see Fig. 21.2).

Question 31

Describe the position of an object with respect to a concave mirror when the mirror produces a virtual image. Is the image in front of the mirror or behind it?

Question 32

The total magnification of a compound microscope is a multiple of the magnification of each lens.

Question 33

The final image formed by a compound microscope is real.

Question 34

The meaning of negative magnification is that the image is smaller than the object.

Question 35

Due to hyperopia, a person has a near point at 70 cm. What is the focal length of the glasses prescribed to correct the person's sight?

Question 36

For a person with myopia, a corrective lens is used to bring the image of a distant object to the retina.

Question 37

For a convex mirror, the focal length is f = -½ R.

Question 38

Due to myopia, a person has a near point at 40 cm. What is the refractive power of the glasses prescribed to correct the person's sight?

Question 39

Figure 21.1 The figure shows the real and apparent positions of a fish in water.
We are looking at a fish from directly above (Fig. 21.1). If the fish looks to us to be 30 cm beneath the surface, where is its real position as measured from the surface? Indices of refraction are, for air n₁ and water n₂, n₁ = 1 and n₂= 1.33.

Question 40

If a light ray comes directly perpendicular to the surface of a mirror, the angle of incidence is 90°.

Question 41

What are the characteristics of images formed by the objective and the eyepiece of a compound microscope?