• Energy from the Sun travels as
electromagnetic waves or EM waves.
• They are waves that transfers energy though
• Do not require matter to transfer its energy—
occurs in a vacuum.
Ocean waves need water
Sound waves need air.
Parts of a Wave
1. Crest- High point of wave.
2. Trough- Low point of wave.
Described by their physical wave features
3. Amplitude- Height of wave from center line
to crest or trough.
4. Wavelength- Distance b/w 2 crests or
5. Frequency- # of waves passing a point
Diagram of a Wave
• Arranged according to their increasing
frequency and decreasing wavelength.
• All electromagnetic waves travel at the
• Amt of energy carried by an
electromagnetic wave increases with
• Each wavelength of EM energy interacts with
objects on Earth in a different way.
• Some are reflected and some are absorbed.
• Color results from a combination of both
• When light strikes a leaf, leaf absorbs red
light and but reflects green light.
• Reflected green light enters your eye—so
you see a green leaf.
• Each type of matter has its own signature,
called a reflectance curve, that shows how
it reflects and absorbs energy.
• A reflectance curve is a graph that shows
how a type of matter reflects visible, infrared
and other wavelengths of light.
• Upward curve on graph indicates more of the
wavelength is reflected.
• Downward curve on graph shows more of
the wavelength is absorbed.
• Lowest frequencies and longest wavelengths.
• TV broadcast- Sound portion carried by AM
waves (amplitude modulation) while picture
portion carried as FM waves (frequency
• MRI- magnetic resonance imaging. Does not
• Radio telescopes
• Microwaves-highest frequency rw. Food
Most common use is cell phones.
• Cannot be seen
• Can be felt as heat- light bulbs, stove, sun.
• Warmer object= more infrared rays
• Cool object= absorb energy from infrared
waves and become hotter.
• Infrared lamps keep food hot, relieve sore
muscles, and dry paint and hair.
• Infrared camaras
• Study pieces of art
• The only electromagnetic waves you can see.
• ROY G BIV red, orange, yellow, green, blue,
indigo and violet.
• Half of energy given off by sun is visible light.
• Essential for photosynthesis.
• Electromagnetic waves with frequencies just
higher than visible light.
• Energy of UV rays can kill cells.
• Used to kill germs in hospitals
• Preserve food in processing plants.
• Can be seen by many insects.
• UV rays cause your skin cells to produce
• Tanning is body’s way of protecting itself from
UV rays. Can cause damage to skin, eyes
and immune system
• Energy of X-rays allows it to pass through
• Used to take pictures of bone because bone
• Exposure of X-rays over a long period of time
can cause defects in cells.
• Been detected deep in space-believed to be
in exploding stars.
• Highest frequencies and shortest
• Have highest energy in spectrum.
• Radioactive materials and nuclear reactions
emit gamma rays.
• Can penetrate 3-m of concrete.
• Gamma camara-patient is injected with a fluid
that emits gamma rays. Move the camara
over the body to form an image.