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Slide 1
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Slide 2
+ Lenses and Mirrors Mrs. Gergel
Slide 3
+ Refraction of light When light rays enter a new medium at an
angle the change in speed causes them to bend, or change direction
Refraction can cause you to see something that may not actually be
there Mirage Rainbows
Slide 4
+ Index of refraction Light slows down as it passes mediums It
travels fastest in air and slowest through glass Glass causes light
to bend more than either air or water because glass refracts light
more Index or refraction- a measure of how much a ray of light
bends when it enters new material The higher the index refraction
of a medium the more it bends light
Slide 5
+ Index of Refraction
Slide 6
+ Prisms and Rainbows When white light enters a prism each
wavelength is refracted by a different amount When white light from
the sun shines through tiny drops of water, a rainbow may appear
Raindrops act like tiny prisms, refracting and reflecting light and
separating colors Colors of the rainbow always appear in the same
order because raindrops refract the shorter wavelengths the
most
Slide 7
+ Mirages A mirage is an image of a distant object caused by
refraction of light
Slide 8
+ Mirage Video
Slide 9
+ Lenses Lens is a curved piece of glass or other transparent
material that is used to refract light A lens forms an image by
refracting light rays that pass through it Lenses have different
shapes Convex Concave The type of image formed by a lens depends on
the shape of the lens
Slide 10
+ Concave Lenses A concave lens is thinner in the center than
at the edges As parallel rays of light pass through a concave lens,
they are bent away from the center of the lens Because the light
rays never meet, a concave lens can produce only a virtual
image
Slide 11
+ Virtual Image Virtual image- are right side up, or upright We
see virtual images because brain assumes that light travels in a
straight line. The brain treats the light rays as though they were
coming from behind the mirror instead of being reflected
Slide 12
+ Convex Lenses Convex lens is thicker in the center than at
the edges As parallel light rays pass through a convex lens, they
are bent toward the center of the lens Rays meet at the focal point
of the lens and then continue on The curved the lens, the more it
refracts light The type of image formed by a convex lens depends on
the position of the object in relation to the focal point. It may
be a virtual image or a real image.
Slide 13
+ Real Image If the object is farther away from the mirror/lens
than the focal point, the reflected rays form a real image Real
image is formed when rays actually meet at a point Real images are
upside down or inverted A real image may be larger or smaller than
the object
Slide 14
+ Activity!
Slide 15
+ Mirrors A mirror is a sheet of glass that has a smooth,
silver-colored coating on one side. When light passes through the
glass, the coating on the back reflects the light regularly,
allowing you to see an image An image is a copy of an object formed
by reflected or refracted rays of light Mirrors can be flat or
curved the shape of the surface determine how the image will
look
Slide 16
+ Plane Mirrors Plane mirror- a flat mirror that produces an
upright virtual image the same size as the object The image you see
in a plane mirror is a virtual image Virtual image- are right side
up, or upright We see virtual images because brain assumes that
light travels in a straight line. The brain treats the light rays
as though they were coming from behind the mirror instead of being
reflected
Slide 17
+ Concave Mirror A mirror with a surface that curves inward
like the inside of a bowl is a concave mirror Focal point is the
point at which the rays meet Concave mirrors can form either
virtual images or real images The type of image depends on the
position of the object in relation to the focal point
Slide 18
+ Convex Mirror A mirror with a surface that curves outward is
called a convex mirror The focal point of a convex mirror is the
point from which the rays appear to come Since the rays do not
actually meet, images formed by convex mirrors are always
virtual