1. Light and Optics
Section

2. Early Ideas About Light
Pythagoras (Greece- you know, a2 + b2 = c2)
Thought that light beams come out of a person’s eyes (like Cyclops)
Problem: then why can’t we see in the dark?

3. Early Ideas About Light Cont…
Al-Haytham (Arab)
Studied vision
Decided that light bounces off objects and into our eyes (sorry Pythagoras)

4. Early Ideas About Light Cont…
Euclid (Greece)
Saw that if you shine a beam of light on a flat mirror, the angle of the incoming beam is equal to the reflected beam
Light travels in straight lines!
Wow, he discovered the law of reflection!

5. Early Ideas About Light Cont…
Sir Isaac Newton (English)
By shining light through a prism Newton discovered that white light is actually made of of a mixture of different colours

6. Early Ideas About Light Cont…
First accurate recording of the speed of light was done in the 1920’s using two mirrors, a beam of light and extremely accurate timing tools.
They calculated it to be: c= 299,798km/s

7. Early Ideas About Light Cont…
Some Properties of light are =>
Light travels in straight lines
Light can be reflected
Light can bend
Light is a form of energy

8. Optical Devices An optical device is an technology that uses light
By that definition can we name some optical devices??

9. Optical Devices Cont… Microscopes use two lenses to magnify objects.
When light shines through the specimen it is magnified and visible to the human eye.

10. Two types of telescopes:
Optical Devices Cont…
Two types of telescopes:
Refracting- 2 lenses, one at each end, Large lens gathers and focuses light towards eyepiece.
Reflecting- uses a concave mirror that gathers light and reflects it off another mirror into the eyepiece.

11. Optical Devices Cont…
Binoculars are in essence two refracting telescopes put together. While they are not as powerful they are generally more convenient.