Transcript Light Waves - Mr. Brown`s Science Town


A difficult question, thousands of years in
understanding.

Very difficult to study,
since it cannot be
caught, and it is very
difficult to measure.

Light is a wave that travels through the
universe’s electromagnetic field.
 Electromagnetism = a combination of electricity
and magnetism

Light waves do not
need a physical
medium like air.

Frequency – light is caused by the vibrations
of electrons

Wavelength – light waves have crests and
troughs, just like water waves

Speed – the speed of light depends on what it
is traveling through.

299, 792, 485 m/s ≈ 3 x 108 m/s

186,282 miles per second

671 million miles per hour

Can be slowed if passing
through water, glass, etc.

Most light is invisible, because it has
frequencies that our eyes cannot see.

Light with faster frequencies has shorter
wavelengths and higher energy

Speed = wavelength x frequency

Wavelength = 3 x 108 m/s ÷ frequency
Type
Ballpark
Ballpark
Frequency Wavelength
Radio (AM)
106 Hz
300 m
invisible
Radio (FM)
108 Hz
3m
invisible
Microwaves &
Radar
1010 Hz
3 cm
invisible
Infrared
1013 Hz
.03 mm
invisible
Type
Ballpark
Frequency
Ballpark
Wavelength
Visible
4.4 x 1014 Hz
700 nm
Red
4.9 x 1014 Hz
600 nm
Orange
5.1 x 1014 Hz
580 nm
Yellow
5.8 x 1014 Hz
530 nm
Green
6.3 x 1014 Hz
470 nm
Blue
6.9 x 1014 Hz
430 nm
Indigo
7.4 x 1014 Hz
390 nm
Violet
Type
Ballpark
Ballpark
Frequency Wavelength
Ultraviolet
1016 Hz
3 x 10-8 m
invisible
X-Rays
1017 Hz
3 x 10-9 m
invisible
Gamma Rays
(from space)
1018 Hz
3 x 10-10 m
invisible
???
More?
Smaller?
invisible

The only difference between types of light is
how fast it vibrates (frequency)

Radio waves, visible light, and x-rays are all
waves created by vibrating electrons at
different speeds

It can reflect!
Reflection = bouncing off

It can refract!
Refraction = bending when
it passes through

It can disperse!
Dispersion = separating
frequencies of light

It can diffract!
Diffraction = spreading out
and separating (by frequency)

Light is a wave.

Light has frequency and wavelength.

The speed of light in a vacuum is 3 x 108 m/s.

It is the second fastest thing in the universe
(only bad news travels faster).

There are many types of light, which all differ
only by frequency/wavelength

Faster frequency = shorter wavelength =
more energy

In order: Radio, Microwaves, Infrared, Visible
Light, Ultraviolet, X-rays, Gamma Rays

Light reflects (bounces off of objects), like on
a mirror

Light refracts (bends while passing through
objects), like through a glass

Light diffracts (spreads out and separates by
wavelength), like making a rainbow