Light Optics Test Review
A converging lens has a focal length of 30 cm. A 5 cm tall candle is placed at a distance of 10 cm in front of the lens. Determine the image distance.
-15 cm
Lens
-A convex lens causing light rays to converge (converging lens) -A concave lens causing light rays to diverge (diverging lens)
Chromatic Aberration
-Light is refracted as it passes through the lens -each color as a different index of refraction therefore each light has a different path -each path has a different focus there for each color has a different focus point
Curved Mirrors
-Mirror is shaped as if it were a section of a hollow sphere with a reflective surface -the distance from the geometric center (C) to the mirror is called the radius of curvature -the line through the geometric center and perpendicular to the surface is called the principal axis -light rays that are parallel to the principle axis converge at the focal point. the length from the mirror to the focal point is called the focal length
Curved Mirrors
-Real Images are formed when the reflected ray converge -Virtual Images are formed when the reflected rays will not converge. Extend the reflected rays back behind the mirror where they will intercept -An image is upright the orientation of the image is the same as the object -An image is inverted the orientation of the image is the opposite of the image
Farsighted (hyperopia)
-focal length of the eye is too long to focus light at the retina -images forms behind of the retina -this is corrected with a convex lens, causing the light to converge
Nearsightedness (myopia)
-focal length of the eye is too short to focus light at the retina -images forms in front of the retina -this is corrected with a concave lens, diverging the light
Spherical Aberration
-occurs when parallel rays far from the principal axis converge away from the mirror's focal point -all parallel rays converge at a parabolic mirror's focal point
Properties of Mirrors and Lens
-ray is reflected back at the incidence angle -image is oriented in the same direction as the object, the image is upright -image height is the same as the object height -images is formed from diverging light, the image us virtual
-Image distance is (+) then the image is _____ -Image distance is (-) then the image is _____
-real -virtual
Which of the following needs to be true for there is be total internal reflection of light
-the index of the incident material is greater than the index for the refracting material - the optical density of the refracting material is less than that of the indicent material -the angle of incidence is greater than the critical angle
-m is (+) the image is _____ -m is (-) the image is _____ -m= 1 _____ -m< 1 _____ -m> 1 _____
-upright -inverted -same size -reduced -enlarged
Draw the Ray Diagrams for a Concave Mirror
1) A ray parallel to the principal axis and reflected back through the focal point 2) A ray through the focal point and reflected back parallel to the principal axis The point where two of the rays intersect is the point of the image, you can draw from the principal axis to the converging lines to form your image.
Draw the Ray Diagrams for a Convex Lens
1) A ray parallel to the principal axis that will converge through the focal point 2) A ray through the optic center, will not change its path after traveling through the lens
Draw the Ray Diagrams for a Concave Lens
1) A ray parallel to the principal axis that will diverge away from the focal point 2) A ray through the optic center that will not change its path after traveling through the lens
Draw the Ray Diagrams for a Convex Mirror
1) A ray to the surface as if you were going through the focal point, reflect it back parallel to the principal axis 2) A ray parallel to the principal axis, reflected back in line with the focal point Extend the reflected rays back behind the mirror, when they intersect is the point of the image. From the principal axis to the point is the image
The speed of light in some transparent material is 2.1x108 m/s. What is the index of refraction for the material.
1.43
Light passes from air into another medium at an angle of 25 degrees to the normal. If the angle or refraction is 15 degrees, what is the index of refraction of the new medium?
1.63
In the index of refraction is equal to 1.75, what is the speed of light in that material
1.71x108m/s
Mirror and Lens Equation
1/do + 1/d1 = 1/f
An object 1m tall is 4m in front of a vertical plane mirror. An observer is 8m in front of the mirror sees an image of the object that is
1m tall and 4m behind the mirror
The focal length of a spherical concave mirror having a radius of 40cm is
20cm
The image of an object 4cm from a converging lens having a 5cm focal length if formed at a distance from the lens of
20cm
If the angle of incidence of light traveling through air, and then striking water is 35 degrees what is the angle of refraction? (n=1 air, n= 1.53 water)
22 degrees
The image of an object 12cm from a concave mirror is twice as tall as the object. The distance. of the image from the mirror is
24cm
The distance of an object from a converging lens in varied until both object and image are 50cm from the lens. The focal lenth of the lens is
25cm
An object is 60cm from a concave mirror whose focal length is 20cm. The distance of its image from the mirror is
30cm in front of the mirror surface
An object is 20cm from converging lens having a 4cm focal length. The image is formed at a distance from the lens of
5cm
You want to take a picture of your image in your bathroom mirror at home by a manual focus camera. If you are standing 3.0 m in front of your mirror, on what distance should you set your camera as the distance of the object
6.0m
An image is located at 5 cm from the convex lens and the focal length is 3 cm. Where is the object located?
7.5 cm
Which of the following is NOT true about the speed of light
Can be greater than 3x108 m/s
A Concave lens is a __________ device.
Divergent
Which of the following is true about the index of refraction
It is always equal to 1 or greater than
Magnification Equation
M= hi/ho = -di/do
If an object is located 15 cm from the convex lens and the focal point is also at 15 cm, what kind of image is formed?
No image
Dispersion of Light
Red n= 1.50 Orange n= 1.506 Yellow n= 1.511 Green n= 1.517 Blue n= 1.523 Violet n= 1.530
Law of Reflection
The angle of incidence is equal to the angle of reflection (specular reflection)
Diffused Reflection
The reflection of the light or other waves or particles from a surface such that a ray incident on the surface is scattered at random angles rather than at just one angle
Symbol n: index of refraction c: speed of light in a vacuum v: speed of light in the medium
Units No Units m/s m/s
Symbol n1: index of refraction of the first medium θ1: angle of incidence n2: index of refraction of the second medium θ2: angle of refraction
Units No Units ° No Units °
Symbol θc: critical angle n1: index of refraction for the incident medium n2: index of refraction for refracting medium
Units ° No Units No Units
A real image can be produced by
a concave mirror
When will a convex lens produce a image that is the same size as the object?
at 2f
When a light ray moves from air into glass at an angle of 45 degrees to the normal, its path is
bent toward the normal
If the size of the object in question 13 is 8cm, the size of the length of F cm to give a virtual magnified image, the object should be placed
between the focus and the lens
Fiber optic cables work because light
cannot escape because of total interanl reflection
Muscles surrounding the eye contract or relax, _____ the shape of the eye and in turn changing the _____ length of the eye
changing; focal
A convex lens is a __________ device.
cnvergent
______ is a lens that is thicker on its edges and makes an object appear smaller?
concave lens
Diverges light rays
concave lens and convex mirrors
Convex Lens and Concave Mirrors
converge light and have a positive focal point
farsighted vision is corrected when _____ lenses allow light rays to focus on the retina
converging
_____ is a lens that is thicker in the middle and makes an object appear bigger
convex lens
Converges light rays
convex lens and concave mirrors
used for security in convenience stores
convex mirror
a light beam from a flashlight reflecting off a sheet of notebook paper
diffused reflection
A virtual image of a point is formed by a mirror when the rays of light leaving that point are reflected from the mirror so that they
diverge
Concave Lens and Convex Mirrors
diverge light and have a negative focal point
Nearsighted vision is corrected when _____ lenses allow light rays to focus on the retina
diverging
Concave Mirror
edges curve towards the observer
A ray of light leaving a source placed at the focus of a converging lens passes through the lens and then
enters the focus on the other side of the lens OR continues in its original direction
What property of waves stays constant during refraction?
frequency
As an object at a very great distance from the converging lens of a camera moves up to one focal distance from the lens, the image moves
from the principal focus to infinity
In what medium does light travel the slowest?
glass
Glass has a _____________ index of refraction than air.
greater
A concave mirror having a focal length F produces a real image that is smaller that the object, when the distance of the object from the mirror is
greater than 2F
A diverging lens can produce
images that are smaller than the object
Each time the light strikes the surface, the angle of _____ is larger than the _____ angle, and therefore, the light is kept within the _____
incidence; critical; fiber
The object in question 5 is 10cm tall. As it moves toward the concave mirror until it reaches the focus of the mirror, the size of the image
increases indefinitely
A real image formed by a single lens will always be
inverted
The image formed by a convex mirror
is always virtual and smaller than the object
Which explains why the fork looks different under water?
light is refracted at an angle
There is only a critical angle if
n1 ≥ n2
Snell's Law Equation
n1sinθ1 = n2sinθ2
Index of Refraction Equation
n= c/v
The bending of light by a lens is a result of — refraction: What is the index of refraction of a refractive liquid if the angle of incidence in the air (ni= 1.00) is 65 degrees and the angle of refraction is 25 degrees?
nr= 2.14
Light impulses from a source enter one end of the _____ _____
optic fiber
Specialized cells on the retina absorb this light and send information about the image along the _____ _____ to the brain
optic nerve
Rays parallel to the principal axis of a concave mirror are reflected so that they
pass through the focus of the mirror
A ray of light passing through the center of a thin diverging lens
passes through without much change of direction
Each color has a different index of _____; therefore each color has its own _____ of refraction
refraction; angle
Lens of the Eye
responsible for focusing light onto the retina that is at the back of the eye
Total Internal Reflection Equation
sinθc = n2/n1
a light beam bouncing off a mirror is
specular reflection
The cause in chromatic aberration in lens is
the differential refraction by the lens of different colors of light
what does the variable "n" stand for
the index of refraction
The Law of Reflection: The angle of incidence is _________ the angle of reflection
the same as
what does the variable "c" stand for
the speed of light in a vacuum
what does the variable "v" stand for
the speed of light in some transparent material
which of the following best describes a convex lens
thicker in the middle than the edges
In what medium does light travel the fastest?
vacuum
The speed of light is 3x10^8 in a _____
vacuum
An image that forms at a location from which the real light rays appear to come together but do not actually cross
virtual
When will a convex lens not produce an image
when the object is at the focal length
When will a convex lens produce an enlarged real image?
when the object is between f and 2f
When will a convex lens produce an reduced real image?
when the object is greater than 2f away from the lens
When will a convex lens produce an enlarged virtual image?
when the object is less than a focal length away from the lens
Convex Mirror
where the edges are away from the observer
