Lights and Optics, position and orientation

Lights and Optics

1. Optics
&

2. Light
➢Something that makes vision possible
➢electromagnetic radiation of any wavelength that
travels in a vacuum with a speed of about 186,281 miles
(300,000 kilometers) per second
➢Light travels almost a million times faster than sound.
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3. Where does light come from?
➢Luminous Objects — emit light from within
➢Illuminated Objects — reflect externally supplied light

The stars
The sun
The moon Electric lights
Fires and flames
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4. Properties & Sources of Light
➢Light travels almost unimaginably fast and far.
➢Light carries energy and information.
➢Light bounces and bends when it comes in contact with
objects.
➢Light has color.
➢Light has different intensities, it can be bright or dim.
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5. Light carries Energy & Power
➢Light is a form of energy that travels.
➢The intensity of light is the amount of energy per second
falling on a surface.
➢Most light sources distribute their light equally in all
directions, making a spherical pattern.
➢Because light spreads out in a sphere, the intensity
decreases the farther you get from the source.
Light carries Information
➢The fiber-optic networks you read about are pipelines
for information carried by light.
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6. air
glass
➢ Refraction is the bending of light
➢ When the light passes from one
medium to another.
Refraction of Light
Reflection of Light
Bending or change in
direction of a light beam
that occurs at the surface
of a substance or object.
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7. air
glass
normal
angle of
refraction
angle of incidence
Reflection of light
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8. Law of Reflection
The angle of
incidence equals
the angle of
reflection.
The incident ray
strikes the mirror.
The reflected ray
bounces off.
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9. Refraction
➢Light rays may bend as they
cross a boundary from one
material to another, like from
air to water.
➢This bending of light rays is
known as refraction.
➢The light rays from the straw
are refracted (or bent) when
they cross from water back
into air before reaching your
eyes.
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10. Refraction
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11. sin i is directly proportional to sin r.
sin i
sin r
O
Relation between angle of incidence and angle of refraction
i = angle of incidence
r = angle of refraction
straight line passing through the origin
Refraction
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12. off a smooth surface (i.e. mirror)
off a rough surface (i.e. white paper)
Seculars Reflection
Diffuse Reflection
Reflection of Light
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13. How does Light travel?
➢Light rays travel in straight lines from the light source.
➢When it hits an opaque object, some light is absorbed and
the rest reflects off.
➢If the object is transparent, light rays pass through it
easily.
➢If the object is translucent, some light can pass through,
but the rest of the light will be reflected.
light
source
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14. Color and Vision
➢When all the colors of the rainbow are combined, we do
not see any particular color.
➢We see light without any color.
➢We call this combination of all the colors of light "white
light".
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15. Color & Vision
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16. ➢We can think of different colors
of light like balls with different
kinetic energies.
➢Blue light has a higher energy
than green light, like the balls
that make it into the top window.
➢Red light has the lowest energy,
like the balls that can only make
it to the lowest window.
Color &Vision
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17. Dispersion and Prisms
➢When white light passes through a glass prism, blue is
bent more than red.
➢Colors between blue and red are bent proportional to
their position in the spectrum.
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18. Dispersion and Prisms
➢The variation in refractive
index with color is called
dispersion.
➢A rainbow is an example of
dispersion in nature.
➢Tiny rain droplets act as
prisms separating the
colors in the white light
rays from the sun.
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19. How the human eye sees color
➢The retina in the back of the eye
contains photoreceptors.
➢These receptors release chemical
signals.
➢Chemical signals travel to the brain along
the optic nerve.
optic nerve
➢Which chemical signal gets sent
depends on how much energy the light
has.
➢If the brain gets a signal from ONLY
green cones, we see green.
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