slide1
Download
Skip this Video
Download Presentation
Light

Loading in 2 Seconds...

play fullscreen
1 / 17

Light - PowerPoint PPT Presentation


  • 222 Views
  • Uploaded on

Light. Where does light come from?. Our major light source: the Sun. Where else does light come from?. Sorting light sources. Natural vs. Man-made (artificial). Are these light sources?. moon. mirror. water.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Light' - magar


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide2
Where does light come from?

Our major light source:

the Sun

slide4
Sorting light sources

Natural vs. Man-made (artificial)

slide5
Are these light sources?

moon

mirror

water

These items are not light sources, instead they are reflecting light from other sources.

slide6
How does light travel?

light

source

  • 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.
slide7
How do we see?
  • Light coming from, (or reflecting off) objects enters the eye through the cornea then the pupil.
  • It is focused clearly by the lens on to the retina.
  • The light sensitive cells of the retina gather information about patterns of light and dark, colour and movement and send it through the optic nerve.
slide8
How do we see?
  • Information entering the brain through the optic nerve, is then transmitted through more nerve pathways to the visual cortex.
  • Here the patterns of light and dark, colour and movement are interpreted.
  • The brain, based on past experience, can then understand what it ‘sees’.
slide9
How do we see colour?

light

source

  • Light from most light sources looks white, but actually contains all the colours of the spectrum; also known as the rainbow.
  • If an object looks blue, it is absorbing every colour except blue, which is reflecting off it and entering your eyes.
  • If an object looks orange, it is absorbing every colour except orange, which, again, is reflecting off and entering your eyes.
  • If an object looks red... (You get the idea!)
slide10
on

off

How does light reflect?

Angle of incidence

Angle of reflection

The ‘angle of reflection’ is always equal to the ‘angel of incidence’.

slide11
on

off

Light can only be reflected in straight lines.

slide12
How does light form shadows?

light

source

light

source

  • Light rays travel in straight lines, radiating out from the light source.
  • If rays are blocked by an opaque object a shadow forms where the light cannot reach.
  • If the light source is moved closer to the object, more light is blocked and a larger shadow is formed.
slide13
How does sunlight cause shadows?

12am

Looking North, the Sun appears to rise in the East...

2pm

10am

The position of the Sun effects the position and length of the shadows created.

9am

3pm

8am

4pm

6am

7pm

Thanks to this natural phenomenon a sundial is able to tell us the time, as long as it is a sunny day!

...and travel across the sky until it sets in the West.

slide14
Now explain to your partner:

What is the difference between light from the Sun and light from the moon?

Why does the Sun rise in the East and set in the West?

Why does an orange look a different colour to a banana?

How does a periscope work?

Why can’t we see anything without a light source?

slide15
Transparent objects allow you to see clearly through them. Some examples are:

Why is it important for these objects to be transparent?

slide16
Translucent objects only let some light through them. You cannot see clearly through a translucent object. Some examples are:

Why don’t we have to see through these objects?

slide17
Opaque objects do not let any light through them. You cannot see through them. Some examples of opaque objects are:

Why is it important that these objects are opaque?

ad