Unit c light and optics

1. Light And
Optics
Unit C

2. Light
Sources

4. Incandescent Light
Incandescent light: when an object is heated to such a high
temperature that it emits visible light.
Example: candle flames and light bulbs
Note: 95 percent of the energy given off by incandescent light bulbs
is released as heat. That's why light bulbs are hot! In a way, an
incandescent source of light is like having a small electric heater in
the room.

5. Fluorescent Light
Fluorescent Light: Invisible ultraviolet light is
absorbed by the particles. These particles then
glow and emit light we can see (visible light).
In a fluorescent light tube an electric current from
the wires causes the mercury vapour inside the
tube to give off ultraviolet radiation. A phosphor
coating on the inside of the tube absorbs the
ultraviolet energy. This causes the coating to
glow, thus producing light that you can see.
Example: ‘Black light’, fluorescent light tubes

6. Fluorescent Light
Advantages:
• Don’t get as hot as incandescent lights
• They lose less energy and are energy efficient
Disadvantages:
• More expensive
• Harder to dispose of
• Chemicals inside can be toxic

7. Phosphorescent Light
Phosphorescent Light: similar to a
fluorescent source. Light energy is
absorbed by certain particles that can
store this energy for a while. The stored
energy is later released as visible light.
Example: Anything that has that green
glow in the dark color to it. Glow in the
dark star stickers you can put on your
ceiling.

8. Fluorescent vs. Phosphorescent Light
• Particles in the fluorescent source release their light energy
immediately. Phosphorescent particles take longer to emit light.
• Phosphorescent light also continues to glow for a while after the
energy source has been removed

9. Chemiluminescent Light
Chemiluminescent Light: When a
chemical reaction produces
energetic particles that give off
visible light energy.
Example: Glow sticks (The
chemicals inside the tube when you
crack it react and glow)

10. Bioluminescent Light
Bioluminescent Light: Chemical
reactions that happen inside living
creates to create a glowing
chemical
Example: Creatures at the bottom
of the ocean (The angular fish that
attacks dory in finding nemo)

11. Electromagnetic
Spectrum

12. Wave Model of Light
Light is a form of energy.
Both energy and light travel in waves.

13. Wave Model of Light
Copy this diagram in your notes
frequency

14. Wave Model of Light
Crest: Highest point on the wave
Trough: Lowest Point on the wave

15. Wave Model of Light
Wavelength: is the distance
from one point of one wave to
the matching point on the next
wave.
Amplitude: is the height from
middle of wave to the crest
(highest point) or middle to
the trough (lowest point)

16. Wave Model of Light
Frequency: the number
of waves that occur in a
given time. (waves per
second)

17. Wave Model of Light
Light is the wavelength of energy we see.
Each color has its own wavelength AND frequency

18. Electromagnetic Spectrum
Light is one form of energy.
There are many other forms of energy that also travel ​in waves.
They all form the Electromagnetic Spectrum.
Electromagnetic Spectrum: the range of wavelengths or frequencies
of all forms of energy

19. Electromagnetic Spectrum
Sketch the following diagram:

20. Electromagnetic Spectrum

21. Electromagnetic Spectrum
Think about the radio channels you listen to in the car. The numbers
come from the frequency the station is at. Think about 91.7 and 96.3.
96.3 has a higher frequency and more energy. The waves are shorter
and more often. AM Radio is lower energy than FM Radio.

22. Light &
Colors