Ray Optics Flashcards
(174 cards)
1
Q
What is the law of reflection?
A
The angle of incidence is equal to the angle of reflection.
2
Q
True or False: Light travels in straight lines.
A
True.
3
Q
Fill in the blank: The point where rays of light converge is called the ______.
A
focus.
4
Q
What is the formula for the lens maker’s equation?
A
1/f = (n-1)(1/R1 - 1/R2).
5
Q
What type of lens is thicker at the center than at the edges?
A
Convex lens.
6
Q
What is the focal length of a concave lens?
A
Negative.
7
Q
Define refraction.
A
The bending of light as it passes from one medium to another.
8
Q
What does the term ‘total internal reflection’ refer to?
A
The phenomenon where light is completely reflected within a medium.
9
Q
Multiple Choice: What is the critical angle for total internal reflection?
A
The angle of incidence that results in an angle of refraction of 90 degrees.
10
Q
What happens to light when it passes from a denser medium to a rarer medium?
A
It bends away from the normal.
11
Q
True or False: A plane mirror produces a real image.
A
False.
12
Q
What is the relationship between the object distance (u), image distance (v), and focal length (f) for a concave mirror?
A
1/f = 1/v + 1/u.
13
Q
What is the nature of the image formed by a convex lens when the object is placed beyond its focal length?
A
Real and inverted.
14
Q
Fill in the blank: The distance between the lens and the focus is called the ______.
A
focal length.
15
Q
What type of image is formed by a concave mirror when the object is placed between the focus and the mirror?
A
Virtual and upright.
16
Q
Define magnification in optics.
A
The ratio of the height of the image to the height of the object.
17
Q
Multiple Choice: Which of the following lenses can produce both real and virtual images?
A
Convex lens.
18
Q
What is the principal axis of a lens?
A
A straight line passing through the center of the lens perpendicular to its surfaces.
19
Q
True or False: The focal point of a concave lens is on the same side as the object.
A
True.
20
Q
What is the effect of increasing the curvature of a lens on its focal length?
A
The focal length decreases.
21
Q
Fill in the blank: The image formed by a convex lens when the object is at infinity is ______.
A
point sized.
22
Q
What type of mirror is used in rear-view mirrors of vehicles?
A
Convex mirror.
23
Q
What is the significance of the refractive index?
A
It determines how much light bends when entering a medium.
24
Q
What is the formula for calculating the refractive index (n)?
A
n = sin(i)/sin(r).
25
Multiple Choice: Which phenomenon explains the formation of rainbows?
Refraction and dispersion.
26
Define the term 'virtual image'.
An image that cannot be projected on a screen.
27
What is the effect of a diverging lens on parallel rays of light?
It spreads them apart.
28
Fill in the blank: The lens formula for a convex lens is ______.
1/f = 1/v - 1/u.
29
What is the relationship between the image distance and the object distance for a convex mirror?
Image distance is always negative.
30
True or False: The image formed by a concave lens is always virtual.
True.
31
What is the purpose of a lens in optical instruments?
To focus or disperse light rays.
32
What happens to the image distance when the object is moved closer to a convex lens?
The image distance increases.
33
Multiple Choice: Which of the following correctly describes the image produced by a convex lens when the object is placed at the focus?
Image is at infinity.
34
What does a higher refractive index indicate about a material?
It is denser and light travels slower in it.
35
Fill in the blank: The distance from the optical center to the focus of a lens is known as ______.
focal length.
36
What type of image is formed by a plane mirror?
Virtual and laterally inverted.
37
True or False: The image formed by a convex lens is always real.
False.
38
What is the effect of increasing the object distance on the size of the image formed by a convex lens?
The size of the image decreases.
39
Define 'dispersion' in optics.
The separation of light into its component colors.
40
What is the critical angle for total internal reflection in water (n = 1.33)?
Approximately 48.6 degrees.
41
Fill in the blank: The image formed by a concave mirror is real when the object is placed ______.
beyond the center of curvature.
42
What is the principal focus of a lens?
The point where parallel rays converge after passing through the lens.
43
Multiple Choice: Which type of lens is used to correct hyperopia?
Convex lens.
44
What is the main principle behind optical fibers?
Total internal reflection.
45
What is the wavelength range of light in the electromagnetic spectrum?
About 400 nm to 750 nm
46
What is the speed of light in vacuum?
c = 2.99792458 × 10^8 m s–1 or approximately 3 × 10^8 m s–1
47
What is a ray of light?
A straight line along which light travels
48
What are the phenomena studied in ray optics?
* Reflection
* Refraction
* Dispersion
49
What is the angle of reflection?
The angle between the reflected ray and the normal to the reflecting surface
50
What is the pole of a spherical mirror?
The geometric center of the spherical mirror
51
What is the principal axis of a spherical mirror?
The line joining the pole and the center of curvature of the spherical mirror
52
What is a sign convention in optics?
A method for measuring distances to derive formulas, where distances in the direction of incident light are positive
53
How is the focal length of a spherical mirror denoted?
f
54
What is the relationship between focal length and radius of curvature of a spherical mirror?
f = R/2
55
What is the principal focus of a concave mirror?
The point where reflected rays converge on the principal axis
56
What is a real image?
An image formed where rays actually converge
57
What is a virtual image?
An image formed where rays appear to diverge from a point
58
What is the mirror equation?
1/f = 1/v + 1/u
59
What does linear magnification (m) represent?
The ratio of the height of the image (h') to the height of the object (h)
60
What is the formula for magnification (m)?
m = -h'/h = -v/u
61
What happens to the image when half of a concave mirror is covered?
The image will be that of the whole object, but the intensity will be reduced
62
What is the effect of the distance of an object from a concave mirror on the image formation?
The image position, nature, and magnification depend on the object's distance
63
If an object is placed at 10 cm in front of a concave mirror with a radius of curvature of 15 cm, what is the image distance?
v = -30 cm
64
If an object is placed at 5 cm in front of a concave mirror with a radius of curvature of 15 cm, what kind of image is formed?
A virtual image at 15 cm behind the mirror
65
True or False: The size of the image relative to the size of the object is affected by the sign convention.
True
66
Fill in the blank: The distance between the focus F and the pole P of the mirror is called the ______.
[focal length]
67
What is the significance of the principal axis in optical instruments?
It is used as a reference line for measuring distances and angles in optics
68
What type of image is formed 15 cm behind the mirror?
Virtual image
## Footnote
A virtual image cannot be projected on a screen.
69
What is the magnification formula?
m = v/u
## Footnote
Where m is magnification, v is image distance, and u is object distance.
70
What happens to the speed of the image as the jogger approaches the mirror?
The speed of the image appears to increase substantially
## Footnote
This phenomenon can be observed from a stationary position, such as in a car.
71
What is refraction?
The bending of light as it passes from one medium to another
## Footnote
This occurs due to a change in speed of light in different media.
72
State Snell's law of refraction.
sini/i = n21
## Footnote
Where n21 is the refractive index of the second medium with respect to the first.
73
If n21 > 1, what can be concluded about the angles of incidence and refraction?
r < i
## Footnote
The refracted ray bends towards the normal.
74
What is the relationship between n12 and n21?
1/n12 = n21
## Footnote
This shows how refractive indices are related between two media.
75
What is the critical angle?
The angle of incidence that results in an angle of refraction of 90°
## Footnote
Beyond this angle, total internal reflection occurs.
76
List some typical critical angles for transparent media with respect to air.
* Water: 48.75°
* Crown glass: 41.14°
* Dense flint glass: 37.31°
* Diamond: 24.41°
## Footnote
These values depend on the refractive index of each medium.
77
What is total internal reflection?
When light is completely reflected back into a denser medium without any refraction
## Footnote
This occurs when the angle of incidence exceeds the critical angle.
78
What applications utilize total internal reflection?
* Prisms
* Optical fibres
## Footnote
These applications take advantage of the phenomenon to bend light or transmit signals.
79
How do optical fibres transmit light?
Through repeated total internal reflections along the length of the fibre
## Footnote
This minimizes loss of signal intensity.
80
What is the requirement for fabricating optical fibres?
Very little absorption of light
## Footnote
Achieved through purification and special preparation of materials like quartz.
81
What is the lens maker's formula?
It relates the focal length of a lens to the refractive indices and radii of curvature of its surfaces
## Footnote
This formula is used for designing lenses.
82
What is the significance of the normal line at a spherical surface?
It is perpendicular to the tangent plane at the point of incidence
## Footnote
This helps in determining angles of incidence and refraction.
83
What happens to light at the interface between two media?
Part of the light is reflected and part is refracted
## Footnote
The behavior of light depends on the optical densities of the media involved.
84
Fill in the blank: The apparent depth is the real depth divided by the _______.
Refractive index of the medium
## Footnote
This is particularly relevant for viewing objects submerged in water.
85
What is the relationship between the angles in a triangle formed by small angles in optics?
MN tan —NOM = OM
## Footnote
This expression relates the tangent of angles to the lengths of the sides in the triangle.
86
How is the exterior angle 'i' defined in the context of DNOC?
i = —NOM + —NCM
## Footnote
This equation shows how the exterior angle is derived from other angles in the triangle.
87
What is Snell's law in terms of refractive indices?
n1 sin i = n2 sin r
## Footnote
This law describes how light refracts when passing between two media with different refractive indices.
88
What is the simplified form of Snell's law for small angles?
n1i = n2r
## Footnote
This approximation is useful when dealing with small angles in optics.
89
What does Equation (9.16) represent in terms of refractive index?
n n2 − 1 =n n2− 1
## Footnote
This equation relates object distance, image distance, and the radius of curvature in optics.
90
In the example provided, what is the distance of the image formed when light from a point source in air falls on a spherical glass surface?
100 cm
## Footnote
The image is formed at the same distance as the object from the glass surface.
91
What does the lens maker's formula relate to?
n1 + n2 = 2 - 1
## Footnote
This formula is used to design lenses based on their refractive indices and curvature.
92
What is the thin lens formula?
1/v - 1/u = 1/f
## Footnote
This equation relates the object distance, image distance, and focal length for lenses.
93
What is the definition of magnification (m) for a lens?
m = h'/h = v/u
## Footnote
Magnification is the ratio of the image height to the object height or equivalent distances.
94
What happens to the power of a lens with a shorter focal length?
It increases
## Footnote
A shorter focal length means the lens converges or diverges light more significantly.
95
What is the SI unit for the power of a lens?
Dioptre (D)
## Footnote
1D = 1m–1, indicating the lens's power based on its focal length.
96
What is the effective focal length (f) of two thin lenses in contact?
1/f = 1/f1 + 1/f2
## Footnote
This equation allows the calculation of the focal length for combined lenses.
97
How is the total magnification (m) of a lens combination calculated?
m = m1 * m2 * m3 ...
## Footnote
The total magnification is the product of the magnifications of individual lenses.
98
What does the term 'refraction' refer to in optics?
The bending of light as it passes from one medium to another
## Footnote
Refraction changes the direction of light due to a change in speed.
99
What angle is referred to as 'e' in the context of a prism?
Angle of refraction or emergence
## Footnote
This angle describes the light exiting a prism after refraction.
100
What is the angle of deviation in a prism?
The angle between the emergent ray and the direction of the incident ray, denoted as d.
101
What is the relationship between the angles of incidence and refraction in a prism?
r1 + r2 = A
102
How is total deviation (d) calculated in a prism?
d = (i - r1) + (e - r2) = i + e - A
103
What occurs at minimum deviation (Dm) in a prism?
The refracted ray inside the prism becomes parallel to its base.
104
What is the formula to determine the refractive index of a prism?
n21 = sin[(A + Dm)/2] / sin[A/2]
105
True or False: Thin prisms deviate light significantly.
False
106
What is a simple magnifier or microscope?
A converging lens of small focal length held near an object.
107
What is the linear magnification (m) formula for a simple microscope?
m = 1 + D/f
108
What is the closest comfortable distance for viewing an image formed by a microscope?
Approximately 25 cm.
109
Fill in the blank: The maximum angle subtended by an object at the eye is achieved when it is at the ______.
near point
110
What is the angular magnification (me) of a compound microscope when the final image is at infinity?
me = D/fe
111
What two lenses are used in a compound microscope?
* Objective lens
* Eyepiece lens
112
What is the primary purpose of a telescope?
To provide angular magnification of distant objects.
113
What is the formula for the magnifying power (m) of a telescope?
m = fo/fe
114
What are the main considerations for an astronomical telescope?
* Light gathering power
* Resolving power
115
What is the advantage of using a mirror in reflecting telescopes?
No chromatic aberration and easier mechanical support.
116
What is the largest lens objective currently in use?
40 inches (~1.02 m) at the Yerkes Observatory.
117
Fill in the blank: The largest reflecting telescopes in the world are the pair of ______ telescopes.
Keck
118
What is the equation that governs reflection?
−i = −r'
119
What law governs refraction?
Snell's law: sini/sinr = n
120
What governs reflection and refraction?
Reflection is governed by the equation —i = —r¢ and refraction by Snell’s law, sini/sinr = n.
121
What is the critical angle of incidence (ic)?
The critical angle of incidence ic is the angle for which the angle of refraction is 90°.
122
What happens for angles of incidence greater than the critical angle?
Total internal reflection occurs.
123
What is an example of total internal reflection?
Examples include multiple internal reflections in diamond, totally reflecting prisms, and mirages.
124
What is the Cartesian sign convention for distances?
Distances measured in the same direction as the incident light are positive; those measured in the opposite direction are negative.
125
What does 'f' represent in the mirror equation?
'f' is the focal length of the mirror.
126
How is the focal length (f) related to the radius of curvature (R)?
f is approximately half the radius of curvature R.
127
What is the lens maker's formula?
1/f = (n2 - n1)(1/R1 - 1/R2)
128
What is the SI unit for the power of a lens?
Dioptre (D) where 1 D = 1 m–1.
129
What is the formula for the total power of a combination of lenses?
P = P1 + P2 + P3 + ...
130
What is dispersion?
Dispersion is the splitting of light into its constituent colors.
131
What is the magnifying power (m) of a simple microscope?
m = 1 + (D/f) where D = 25 cm is the least distance of distinct vision.
132
What is the formula for the magnifying power of a compound microscope?
m = me × mo where me is magnification due to the eyepiece and mo is the magnification produced by the objective.
133
What is the relationship between the angles subtended by the object and the image in a telescope?
The magnifying power m is the ratio of the angle b subtended at the eye by the image to the angle a subtended at the eye by the object.
134
True or False: The laws of reflection and refraction apply only to specific surfaces.
False. They are true for all surfaces and pairs of media at the point of incidence.
135
What occurs when an object is placed between f and 2f from a convex lens?
A real image can be seen on a screen placed at the image location.
136
How does the image exist without a screen?
Rays from a given point on the object converge to an image point in space.
137
What is the effect of thick lenses on images?
Thick lenses can give colored images due to dispersion.
138
What is the relationship between angular size and distance in a simple microscope?
The angular size of the object equals the angular size of the image.
139
Fill in the blank: The angular magnification of a simple microscope is inversely proportional to the _______.
focal length of the lens.
140
What is the formula for the effective focal length of several thin lenses in contact?
1/f = 1/f1 + 1/f2 + 1/f3 + ...
141
What happens to the virtual image produced by a convex mirror?
It is always diminished in size and located between the focus and the pole.
142
What is the angular magnification of a telescope?
The angular magnification is given by m = f0/fe.
143
What happens if the object is moved further away from a concave lens?
The image produced by the lens will become smaller.
144
True or False: A convex lens always produces a virtual image.
False. A convex lens can produce both real and virtual images depending on the object distance.
145
What is the refractive index of water if the apparent depth is 9.4 cm and the actual depth is 12.5 cm?
Refractive index = actual depth/apparent depth = 12.5 cm / 9.4 cm.
146
What is the angle of minimum deviation (Dm) for a prism?
It is related to the refractive index by the formula n21 = sin[(A + Dm)/2] / sin(A/2).
147
What is the relationship between distance and magnifying power in a microscope?
The distance between the object and eyepiece affects magnifying power.
148
Fill in the blank: The effective focal length of a lens combination is ________ when lenses are separated by a distance.
dependent on the separation distance.
149
What is the maximum possible focal length of a lens to project an image 3m away?
It is determined by the lens formula and the object distance.
150
What happens when a lens is placed in the path of a convergent beam?
The point of convergence will change based on the lens's focal length.
151
What is the angular magnification of a magnifying glass?
It is defined as the ratio of the angle subtended by the virtual image to the angle subtended by the object.
152
What should be the distance between the object and the magnifying glass for maximum magnifying power?
The object should be placed at the focal point of the lens.
153
What is the relationship between magnifying power and focal length of the lens in a simple microscope?
The magnifying power is inversely proportional to the focal length of the lens.
154
Why must both the objective and the eyepiece of a compound microscope have short focal lengths?
To achieve a higher angular magnification.
155
When viewing through a compound microscope, where should our eyes be positioned for best viewing?
A short distance away from the eyepiece.
156
What is the recommended short distance between the eye and the eyepiece when using a compound microscope?
The specific distance is not provided in the text.
157
What angular magnification is desired using an objective of focal length 1.25cm and an eyepiece of focal length 5cm?
30X.
158
What is the focal length of the objective lens in the small telescope described?
140cm.
159
What is the focal length of the eyepiece in the small telescope described?
5.0cm.
160
What is the magnifying power of the telescope for viewing distant objects when in normal adjustment?
The specific magnifying power is not provided in the text.
161
What is the magnifying power of the telescope when the final image is formed at the least distance of distinct vision (25cm)?
The specific magnifying power is not provided in the text.
162
What is the separation between the objective lens and the eyepiece in the small telescope?
The specific separation distance is not provided in the text.
163
If a telescope views a 100 m tall tower 3 km away, what is the height of the image of the tower formed by the objective lens?
The specific height of the image is not provided in the text.
164
What is the height of the final image of the tower if it is formed at 25cm?
The specific height of the final image is not provided in the text.
165
What type of telescope uses two mirrors?
Cassegrain telescope.
166
How far apart are the mirrors in the Cassegrain telescope described?
20mm.
167
What is the radius of curvature of the large mirror in the Cassegrain telescope?
220mm.
168
What is the radius of curvature of the small mirror in the Cassegrain telescope?
140mm.
169
Where will the final image of an object at infinity be in the Cassegrain telescope?
The specific location of the final image is not provided in the text.
170
What happens to light incident normally on a plane mirror attached to a galvanometer coil?
It retraces backwards.
171
What is the deflection of the mirror caused by a current in the coil?
3.5 degrees.
172
If the reflected spot of light is on a screen placed 1.5 m away, what is being measured?
The displacement of the reflected spot of light.
173
What type of lens is depicted in the experiment with a liquid layer on top of a plane mirror?
Equiconvex lens.
174
What is the refractive index of the liquid if the distance of the needle from the lens changes from 45.0cm to 30.0cm?
The specific refractive index is not provided in the text.
