How does light travel Reflect or Refract In the real world

1
How does light travel?Reflect or RefractIn the
real world!
2
(No Transcript)
3
(No Transcript)
4
How It Works A microscope uses the same trick as
a refracting telescope light waves being bent
as they travel through glass. In a telescope, the
idea is to bend parallel light from very faraway
objects into a small focus at the eye. In a
microscope, the idea is to bend diverging
(spreading-out) light into a parallel path, then
bend that parallel-path light into a small focus
at the eye. Light enters the bottom, travels
through the objective lenses and then through the
eyepiece lenses. by David Garrison To make a
little more sense of that, lets try to magnify
something. Maybe its a dust mite, a tiny bug
that lives in your pillow and eats your dead skin
(ew!). First, we have to light up the dust mite.
A mirror mounted under the microscope stand does
the job. Light bounces off the mirror, passes
through and around our dust mite (mounted firmly
to a microscope slide), and into the objective
lenses. These lenses bend some of the spread-out
light beams from the dust mite into straight line
paths that travel through the microscope tube.
Next, the light beams reach the eyepiece lenses.
These lenses bend the light back into your eye,
so you can see the dust mite up close and
personal. The power of the microscope depends on
how much each lens bends the light. Usually, the
power is written right on the microscope itself.
40x, for instance, means that the image at the
eyepiece is 40 times larger than real life.
5
(No Transcript)
6

• How It Works
• Light enters through the front objective lens and
  then passes through the eyepiece lens before
  reaching your eye.
• by David Garrison
• Refracting telescopes depend on one amazing fact.
  As light passes through glass, it slows down.
  Slowing down a light beam makes it bend. Why?
  Imagine youre pulling a wagon along a sidewalk,
  when the wheels on one side slip off into the
  grass. The wheels turn slower in the grass than
  they do on the sidewalk, and the wagon moves
  toward the grass. In the same way, when a light
  beam passes through a glass lens inside a
  telescope, it moves toward the lens. When the
  light beam comes out the other side, its bent!
• The shape of the lens means light near the top of
  the lens is bent down and light near the bottom
  of the lens is bent up. Somewhere inside the tube
  the light beams cross, but before they can spread
  out again the eyepiece lens bends the light beams
  again and sends them to the eye.
• Because the light beams cross, the image ends up
  upside-down. This doesnt matter much when youre
  looking at Mars or the Moon (remember theres no
  real up or down in space), but refracting
  telescopes used to see objects here on Earth
  often have another set of lenses to flip the
  image right-side up again.
• In a reflecting telescope, light bounces off
  mirrors instead of passing through lenses.
• by David Garrison
• Refracting telescopes are simpler than reflecting
  telescopes, but they have an important
  limitation. Remember that the light passing
  through the glass lens gets bent. It turns out
  that different colours are bent different
  amounts, and that causes the light to become
  unfocused. Isaac Newton solved this problem by
  replacing the lenses with mirrors.
• When light hits a mirror, it doesnt bend.
  Instead, it bounces off. Just like a ball
  bouncing off a wall, a light beam comes off a
  mirror the same way it comes in. In other words,
  the angle in equals the angle out. And that rule
  is true for all the light, no matter its colour.
• The primary mirror in a reflecting telescope is
  curved just the right amount to bounce all the
  light onto the secondary mirror. From there, the
  light passes through the eyepiece lens, which
  bends the light into the eye.

7
(No Transcript)
8

• How It Works
• Light enters the front and bounces off two prisms
  before passing through the eyepiece lens and
  entering your eye.
• by David Garrison
• Binoculars are great for seeing things on Earth
  and in the sky. Suppose you see a strange light
  on the horizon. Have the flying saucers finally
  arrived from Alpha Centauri? You grab your
  binoculars and take a look. When you do, the
  light from the UFO encounters the objective
  lenses (one on each side) of the binoculars. Just
  as in a telescope or a microscope, the glass lens
  bends the light by slowing it down. The bent
  light beams race through the body of the
  binoculars, bouncing off the two prisms before
  they pass through the eyepiece and enter your
  eyes.
• The size and placement of the lenses determine
  just how magnified the image is when it enters
  your eyes. For instance, binoculars rated 7 x 50
  make the image seven times larger. The 50 is the
  size of the objective lens, measured in
  millimetres. The larger the objective lens, the
  more light it gathers from the object. These
  binoculars are just strong enough to make out
  some strange inscriptions on the UFO Goodyear.
  The unidentified flying object has just become an
  identified flying object. Oh, well!

9
(No Transcript)
10

• How It Works
• Every camera is essentially a lightproof box,
  with some method of letting in just a small
  amount of light at just the right time. Once the
  light is in the box, it forms an image (like in
  the camera obscura), causes a chemical reaction
  on photographic film (like in the Brownie
  camera), or energizes a photocell (like in a
  digital camera). To find out how the light gets
  in to do its thing, lets imagine what happens
  when you snap a picture, maybe of a dolphin
  playing in the surf. (You can see right away that
  a camera obscura wouldnt do you much good for
  this kind of picture!)

11
(No Transcript)
12
(No Transcript)
13
(No Transcript)
14
(No Transcript)
15
(No Transcript)
16
(No Transcript)