Chapter 18 - Catawba County Schools

clappergappawpawΠολεοδομικά Έργα

16 Νοε 2013 (πριν από 3 χρόνια και 7 μήνες)

103 εμφανίσεις

Chapter 18

The Electromagnetic Spectrum
and Light

Chapter 18


*Electromagnetic waves
-

transverse waves consisting of
changing electric fields and
changing magnetic fields


Electromagnetic waves are
produced when an electric charge
vibrates or accelerates.



Chapter 18


Electromagnetic waves can travel
through a vacuum, or empty space, as
well as through matter.


*Electromagnetic radiation
-

transfer of
energy by electromagnetic waves
traveling through matter or across
space


The speed of light in a vacuum,
c
, is
3.00 x 10
8

meters per second.


Chapter 18


Electromagnetic waves vary in
wavelength and frequency.


Electromagnetic radiation
behaves sometimes like a wave
and sometimes like a stream of
particles.

Chapter 18


Blue light has a higher
frequency, and
therefore more
energy, and will cause
the emission of
electrons.


Red light, with its
lower frequency,
won’t cause the
emission of electrons.


Chapter 18



*Intensity
-

rate at which a wave
energy flows through a given unit
of area


The intensity of light decreases as
photons travel farther from the
source.


Chapter 18


*Electromagnetic spectrum
-

full
range of frequencies of
electromagnetic radiation


The electromagnetic spectrum
includes radio waves, infrared
rays, visible light, ultraviolet light,
X
-
rays, and gamma rays.

Chapter 18


Radio waves are used in radio and
television technologies, as well as
in microwave ovens and radar.



Radar
-

RA
dio
D
etection
A
nd
R
anging

Chapter 18


Infrared rays are used as a source
of heat and to discover areas of
heat differences.

Chapter 18


People use visible light to see, to help
keep them safe, and to communicate
with one another.


Ultraviolet rays have applications in
health and medicine, and in agriculture.


Vitamin D


Disinfection


Artificial sunlight

Chapter 18


X
-
rays are used in medicine, industry,
and transportation to make pictures of
the inside of solid objects.


Gamma rays are used in the medical
field to kill cancer cells and make
pictures of the brain, and in industrial
situations as an inspection tool.

Chapter 18


Materials can be transparent,
translucent, or opaque.


*Transparent
-

transmits light


*Translucent
-

scatters light


*Opaque
-

absorbs or reflects all light


When light strikes a new medium, the
light can be reflected, absorbed, or
transmitted.


When light is transmitted, it can be
refracted, polarized, or scattered.