wave- up and down movement of energy from one place to another

electromagnetic waves (EM waves)- electric and magnetic energy that travels through empty space in the form of waves moving at the “speed of light”. Stars emit every type of EM wave.

electromagnetic spectrum (EMS)- all the different types of EM wave, from the longest wavelengths (radio waves) to the shortest wavelengths (gamma rays).

Each different type of EM wave has its own unique properties, effects, and uses.

RADIO WAVES: longest w, lowest f, least energy GAMMA RAYS: shortest w, highest f, most energy

Humans cannot see EM radiation (except visible light, as colors) since most wavelengths are too short or too long to be sensed by our eyes. Humans cannot feel EM radiation (except infrared, as heat) since most wavelengths are too short or too long to be sensed by the nerves in our skin.

RADIO WAVES

USES: Radio signals, TV broadcast, satellite communications USES: Radio signals, TV broadcast, satellite communications. Emitted by radio antennae and by stars. May be sent by aliens? EFFECTS: They have the lowest energy, so they are harmless.

Microwaves

USES: Cell phones, radar, cooking.

Infrared Waves

USES: fast food heat lamps, finding people in the dark, measuring temperature SOURCES: anything warm Infrared spy camera

VISIBLE LIGHT - the only EM waves humans can SEE! Makes up only a very small part of the EM spectrum! Has medium wavelength and medium energy, so it is not harmful to organisms.

Ultraviolet (UV) Waves Fluorescent minerals

USES: tanning EFFECTS: Has more energy than visible light, so it may damage skin cells, may cause cancer SOURCES: Stars (like the SUN) Skin cancer on a man’s arm

The earth’s atmosphere contains a very special layer...

… called the OZONE LAYER. The ozone layer protects humans (and other organisms) from the sun’s UV rays.

A large hole has been developing in the ozone layer since the 1970s A large hole has been developing in the ozone layer since the 1970s. The hole is directly above Antarctica, at the South Pole.

The hole in the OZONE LAYER.

X-RAYS

USES: to see inside the body, to see inside luggage, to kill cancer cells, sterilize medical equipment EFFECTS: Has a lot of energy, so it may damage DNA, may cause cancer

Mushroom cloud from atomic bomb GAMMA RAYS

GAMMA RAYS EFFECTS: may damage DNA, may lead to cancer or radiation sickness SOURCES: radioactive elements (U, Ra, Cs-137, Ir-92, Co-60,K-40,Tc-99), nuclear explosions, stars, supernovae

GAMMA RAYS USES: see inside the body, measure blood flow, kill cancer cells (radiation therapy), measure the thickness of metal, find leaks in pipes, strengthen materials, sterilize food & medical equipment, measure properties of rock and soil.

The vertical illustration of the different regions of the e-m spectrum and their common uses was done by Design at Work for the curriculum supplement "Human Physiology in Space" by Barbara F. Lujan and Ronald J. White, 1994. Used by permission.