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radio and tv waves
accelerating charges
Communications remote controls
MRI
Requires controls for band use
microwave
Accelerating charges & thermal agitation
Communications, ovens, radar
Deep heating
Cell phone use
infrared
Thermal agitations & electronic transitions
Thermal imaging, heating
Absorbed by atmosphere
Greenhouse effect
visible light
Thermal agitations & electronic transitions
All pervasive
Photosynthesis, Human vision
ultraviolet
Thermal agitations & electronic transitions
Sterilization, Cancer control
Vitamin D production
Ozone depletion, Cancer causing
x-rays
Inner electronic transitions and fast collisions
Medical Security
Medical diagnosis, Cancer therapy
Cancer causing
gamma rays
Nuclear decay
Nuclear medicine, Security
Medical diagnosis, Cancer therapy
Cancer causing, Radiation damage
transparent
If the material is _ to the particular
frequency, then the wave can largely be
transmitted.
opaque
If the material is _ to the frequency, then
the wave can be totally reflected.
absorbed
The wave can be_ by the material,
indicating that there is some interaction
between the wave and the material, such as the
thermal agitation of molecules.
radio and tv waves
is defined to contain any electromagnetic wave produced by
currents in wires and circuits.
carrier of audio information
amplitude modulation
AM
frequency modulation
FM
50 or 60hz
The lowest commonly encountered radio
frequencies are produced by high-voltage AC
power transmission lines at frequencies of
extremely low frequency
radio waves of
about 1 kHz are used to communicate with
submerged submarines.
AM radio waves
are used to carry commercial
radio signals in the frequency range from 540
to 1600 kHz.
FM radio waves
are also used for commercial
radio transmission, but in the frequency range
of 88 to 108 MHz.
electromagnetic waves
Astronomers and astrophysicists collect signals from outer
space using
pollution
A common problem for astrophysicists is the _
from electromagnetic radiation pervading our surroundings
from communication systems in general.
microwaves
are the highest-frequency
electromagnetic waves that can be produced by
currents in macroscopic circuits and devices.
Microwave frequencies range from about 109
Hz to the highest practical LC resonance at
nearly 1012 Hz.
short wavelengths
produced by accelerating electrons
radar
is a common application of microwaves that was
first developed in World War II.
doppler shift
be used to
determine the speed of a car or the intensity of a
rainstorm.
sophisticated radar systems
used to map the Earth
and other planets, with a resolution limited by
wavelength.
infrared radiaion
radiation is generally produced
by thermal motion and the vibration and
rotation of atoms and molecules.
means “below red”
night-vision scopes
can detect the infrared
emitted by various warm objects, including
humans, and convert it to visible light.
reconnaissance satellites
can detect
buildings, vehicles, and even individual
humans by their infrared emissions, whose
power radiation is proportional to the fourth
power of the absolute temperature.
visible light
is the narrow segment of the
electromagnetic spectrum to which the
normal human eye responds.
produced by vibrations
red light
has the lowest frequencies
and longest wavelengths,
violet
has the highest frequencies and
shortest wavelengths.
blackbody radiation
peaks in the visible part of the
spectrum but is more intense in the
red than in the violet, making the Sun
yellowish in appearance.
optics
is the study of the behavior of visible
light and other forms of electromagnetic
waves.
ray optics
is the study of such situations
and includes lenses and mirrors.
ultraviolet radiation
“above violet”
extend upward from violet, the
highest-frequency visible light.
also produced by atomic and
molecular motions and electronic transitions.
uv a
320-400nm
uv b
290-320nm
causes skin cancer
uv c
220-290nm
x-rays
This radiation was called an _, because its identity
and nature were unknown.
have adverse effects on living cells similar to
those of ultraviolet radiation, and they have the
additional liability of being more penetrating,
affecting more than the surface layers of cells.
gamma rays
The most penetrating nuclear radiation
an extremely high frequency electromagnetic wave.
are any electromagnetic radiation emitted by a
nucleus.
identical to X-
rays of the same frequency—they differ only in
source.
light
is an electromagnetic radiation that has
properties of waves and particles.
echo
is a reflected sound wave.
refraction
is the bending of light as it
passes from one medium to another.
images
are formed when light
strikes a reflecting surface, such
as mirror or lens.
mirrors and lenses
are very
essential in our daily living.
cornea
You can see because of the _
lens of your eye.
plane mirrors
The flat mirror that we can see
everywhere.
When light strike a plane mirror, the light
rays obey the law of plane mirror
concave mirror
a mirror that
curves inward like a hollow inside a
sphere. The light hitting the surface of a
concave mirror that converges.
convex mirror
a mirror that
curves outward, like outside of a sphere.
It diverge the light and creating only
virtual image.
center of curvature (C)
center of the circle
focus (F)
one-half of the radius
vertex (V)
the point where the mirror crosses
the principal axis.
principal axis
a line drawn through the
vertex.
focal length (f)
the distance from the focus
to the vertex of the mirror
radius of curvature
the distance between the
center of curvature to the vertex of the mirror.