Light

1
Light
2
How does light travel?

• With your flashlight, shine a beam of light down
  a hall or across the room.
• What do you notice about the beam? Can you see
  it? Does it seem to travel in a line? Is the path
  curved?
• Shine through glass what is the path of light
  through the glass?

3
We know that

• Light travels in a straight line!

4
Properties of Light

• Light is energy that you can see, and it travels
  through space in the form of waves.
• A wave is an oscillating repetitive motion that
  travels through matter or space.

5
How does light reflect from things?

• What happens when you shine a beam of light on a
  mirror?
• How does the light beam bounce back, or reflect ?
  Shine it at different angles and see what
  happens.
• If you hold the mirror at an angle and shine the
  flashlight on it, does the light bounce back in
  your eyes?

6
How light reflects

• The light is obviously reflecting from the
  mirror, just as you would expect.
• Notice the angle at which the light beam hits the
  mirror and the angle at which it reflects.
• Reflection occurs when light bounces off an
  opaque material.

7
Behaviour of Light

• Light waves travel in a straight line, although
  they can change direction.
• When light waves strike an object light is
  either transmitted, reflected or absorbed.

8
Refraction

• What happens when you dangle your feet in the
  pool? Or when you place a pencil in a glass of
  water? Does the object seem bent at the surface
  of the water?

9
Refraction

• This phenomenon is due to the bending, or
  refraction, of light at the interface between the
  water and the air.
• Refraction occurs when light passes into a
  transparent material.

10
Lenses and Light

• When light passes through a curved transparent
  substance, it is refracted.
• A curved transparent substance is called a lens.