Download 11.1 What is Light?

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Physics: OPTICS
What Is Light?
What is Light?
- The majority of light comes from the Sun
- We see objects that emit or reflect light
- Light travels at high speeds and in straight lines
What Is Light?
Light is a form of electromagnetic radiation that
can be seen by the eye
Radiation: all energy that is transmitted at the
speed of light and that does not require a
medium for transmission
What Is Light?
Light is transferred through radiation & does
not require a medium to travel
Medium: any physical substance that acts as
a carrier for the transmission of energy
Light also travels like a wave...An
electromagnetic wave...
What is an Electromagnetic
Wave?
A wave that is created by the motion of
electrically charged particles that has both
electric and magnetic parts (electricity & magnetism)
All forms of EM radiation travel at the same
speed:
300 000 000 metres/second - (299 792 458 m/s)
Speed
of
Light
Understanding Waves
Understanding Waves
Electromagnetic radiation can be classified
according to the wavelength of the waves
The greater the wavelength = lower the energy light has
Example
Example
High frequency
Short wavelength
Low frequency
Long Wavelength
UV light = High energy
Radio waves = Low energy
Which
wave has
more
energy?
What is the
Electromagnetic Spectrum?
Many forms of electromagnetic radiation
make up the electromagnetic spectrum:
Demo: Viewing the Visible
Spectrum
•
•
•
A triangular prism SLOWS down the speed of light, causing
different COLOURS to slow down at different RATES since
their initial SPEEDS were different.
Red light has the LEAST amount of energy and slowed down
the LEAST
Violet light has the MOST amount of energy and slowed down
the MOST
Uses of Electromagnetic Waves
Type of Wave
Radio Waves
Microwaves
Infrared Light
Visible Light
Use/phenomena
Natural Sources
of Radio Waves
Where do we see this type of electromagnetic radiation
occur naturally?
Artificial Sources
of Radio Waves
Where do we see this type of electromagnetic radiation
used artificially?
Uses of Electromagnetic Waves
Type of Wave
Radio Waves
Microwaves
Infrared Light
Visible Light
Use/phenomena
Radar
Radio, TV signals
Cell phones
Microwaves
Where do we see this type of electromagnetic radiation?
Uses of Electromagnetic Waves
Type of Wave
Radio Waves
Microwaves
Infrared Light
Visible Light
Use/phenomena
Radar
Radio, TV signals
Cell phones
Telecommunications
Microwave ovens
Infrared Radiation
Where do we see this type of electromagnetic radiation?
Uses of Electromagnetic Waves
Type of Wave
Radio Waves
Microwaves
Infrared Light
Visible Light
Use/phenomena
Radar
Radio, TV signals
Cell phones
Telecommunications
Microwave ovens
Lasers
Remote controls
Physical therapy
Keeps food warm
Visible Light
Where do we see this type of electromagnetic radiation?
Uses of Electromagnetic Waves
Type of Wave
Radio Waves
Microwaves
Use/phenomena
Radar
Radio, TV signals
Cell phones
Telecommunications
Microwave ovens
Infrared Light
Lasers
Remote controls
Physical therapy
Keeps food warm
Visible Light
Human vision
Theatre/concert lighting
Lasers
Ultraviolet Radiation
Where do we see this type of electromagnetic radiation?
Uses of Electromagnetic Waves
Type of Wave
UV light
X-rays
Gamma Rays
Use/phenomena
Causes skin to tan/burn
Black lights
Kills bacteria in food
X-rays
Where do we see this type of electromagnetic radiation?
Uses of Electromagnetic Waves
Type of Wave
UV light
X-rays
Gamma Rays
Use/phenomena
Causes skin to tan/burn
Black lights
Kills bacteria in food
Medical imaging (bones, teeth)
Security in airports (baggage)
Cancer treatment
Gamma Rays
Where do we see this type of electromagnetic radiation?
Uses of Electromagnetic Waves
Type of Wave
UV light
X-rays
Gamma Rays
Use/phenomena
Causes skin to tan/burn
Black lights
Kills bacteria in food
Medical imaging (bones, teeth)
Security in airports (baggage)
Cancer treatment
Cancer treatment
Product of nuclear decay
Uses of Electromagnetic Waves
Type of Wave
Use/phenomena
UV light
X-rays
Gamma Rays
Causes skin to tan/burn
Black lights
Kills bacteria in food
Medical imaging (bones, teeth)
Security in airports (baggage)
Cancer treatment
Cancer treatment
Product of nuclear decay
All types of waves are used in astronomy to help produce a
more complete view of the universe!
Understanding Waves
The harmful effects
of exposure to high
energy radiation
range from sunburn
to increased risk of
developing cancer
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Homework!
11.1 Q’s #: 3, 4, 6, 7, 8, 9
11.1
3. Hertz discovered radio
waves in 1887 and
Roentgen discovered Xrays in 1895.
4. Microwaves, infrared
light, red light, X-rays,
gamma rays
6. Red, orange, yellow,
green, blue, indigo, and
violet.
7. Objects in the universe emit many
forms of electromagnetic radiation
besides visible light.
When we detect these other forms of
radiation we can view celestial objects
and events in greater detail.
X-rays = detect black holes, gamma rays
= nuclear processes, UV light = discover
chemical composition of celestial bodies
8. Radio, television,
microwave, cellular phone,
DVD remote
9. a) X-rays, baggage
screening
b) Ultraviolet light, vitamin D
c) Radio waves, radar
d) Infrared light, DVD remote
control
9. e) Microwaves,
telecommunications
f) Gamma rays, cancer
treatment
g) Visible light,
theatre/concert effects