1. Grade 10 Academic Science
Light and Optics Unit

2. Unit Organization Light and Optics Production and Reflection
Refraction
Lenses and
Optical Devices

3. Light is Weird Light is a form of energy visible to the human eye
Light does not need a medium to travel
Light sometimes displays properties of waves and sometimes displays properties of particles
Light travels at m/s
Light takes 8.3 minutes to reach the Earth
Light travels in straight lines if travelling in the same medium
Life on Earth would not exist without light

4. The Electromagnetic Spectrum
An electromagnetic wave is a wave that has both electric and magnetic parts, does not require a medium, and travels at the speed of light
There are many different types of electromagnetic waves
- i.e. x-rays, microwaves, radio waves
Visible light is an electromagnetic wave that the human eye can detect
Visible spectrum of colours: red, orange, yellow, green, blue, indigo, violet
Refer to page 466 in your textbook for more examples of the electromagnetic spectrum

5. Visible Light and the Spectrum
White light is composed of all the colours of the rainbow.
ROYGBIV
red-orange-yellow-green-blue-indigo-violet
A glass prism is capable of separating the colours because each colour travels through the prism at a slightly different speed.

6. Why we see things!
We see things because light hits our eyes from all objects.
Luminous
Something that provides it’s own light
i.e. sun or lightbulb
Non-luminous
Something that reflects or absorbs light
i.e. moon, mirror

7. Sources of Light - Natural
Sunlight (solar radiation)
Stars (burning balls of gas)
Lightning
Core of the Earth (magma)
Bioluminescent objects

8. Sources of Light – Electric Powered
Incandescent lights
Emitting light because of high temperature
Light emitting diodes (LED’s)
Electric Discharge
Use of electricity to excite a gas
Fluorescent Lights
filled with mercury vapour

9. Sources of Light - Combustion
Candles
Fire
Oil lamps

10. Sources of Light - Chemical
Chemiluminescence
Light produced by a chemical reaction
i.e. glow sticks
Bioluminescence
Light produced by a living thing
i.e. fireflies, glow worms, plankton, fish, jellyfish
Phosphorescence
Light produced for some time after receiving energy from another source
i.e. hands on a watch
Fluorescence
Light produced while receiving energy from another source
i.e. black light

11. Incandescent Light
Electricity passes through a filament, causing it be become hot and give off light

12. Light Emitting Diodes (LED’s)

13. Electric Discharge
Electricity causes the gas to glow
E.g. neon sign

14. Fluorescent Light Fluorescent light filled with mercury vapour
current + mercury = UV light
UV light absorbed by fluorescent coating on inner surface of tube

15. Black light

16. Watch

17. Plankton

18. Glowsticks

19. Firefly

20. Glow worms

21. Deep-Sea Fish