Chapter 14.3: The Electromagnetic Spectrum

EM Radiation There are two types of waves: Transverse waves. Compression waves. Sounds, seismic waves, and water waves are compression waves. Light, and again water waves and seismic waves are a type of transverse wave.

Light waves are part of a larger spectrum of waves called electromagnetic radiation, (EM radiation). Sound, seismic and water waves, travel through mediums by vibrating particles. EM are waves of pure energy that can travel through a vacuum, and do not vibrate particles. Vibrating waves of electricity and magnetism.

The sun is the most important source of energy including light and other EM radiation on Earth. When EM radiation is emitted from the sun, it radiates outwards likes spokes on a bicycle wheel. Radiant energy: Energy that travels by radiation, (radiating outwards).

The EM Spectrum Visible light waves are part of a larger electromagnetic spectrum of waves. The rest are of course invisible because our bodies cannot detect/sense them. We have built devices that create or detect these other sources of energy. Radio antenna detects radio waves. WiFi waves and TV signals are microwaves.

The EM spectrum is arranged in order of increasing frequency/decreasing wavelength. This also means increasing energy.

Types of EM Radiation Radio waves have the longest wavelength, the smallest frequency, and the lowest energy compared to other EM radiation. Uses: Radio, television broadcasting, and MRI, (Magnetic Resonance Imaging), in hospitals.

Microwaves are actually radio waves with the shortest wavelength, highest frequency, and highest energy. Uses: Microwave ovens, Telecommunications (television and cellphones), radar, and WiFi.

Infrared waves are shorter and have more energy than radio and micro waves. Heat or heat energy, from Ch. 7, is in fact infrared radiation. Almost everything including us emits infrared radiation. Infrared radiation from Earth contributes to climate change when it is trapped by CO 2 in the atmosphere.

Uses: CD ROM readers in computers, infrared goggles for the military, heat lamps in restaurants, and various scanners for medical and security purposes. The Canadian LANDSAT satellite.

Visible light comes next. Ultraviolet is the first wavelength that is shorter than visible light and contains more energy. Some UV waves penetrate our atmosphere and trigger us to make vitamin D which strengthens our bones and teeth. Too much UV can cause sunburns, cancer, and eye damage.

Uses: Fluorescent objects, sterilizing water, food and medical equipment, UV lights, crime scene investigation technology, and especially in the biological sciences!!!

X-rays have far shorter wavelengths, and much more energy than UV radiation. Discovered in Heavily used by doctors and dentists to scan areas of the body. Used to scan luggage at the airport. Used to look inside machines.

Gamma rays have the most energy and the shortest wavelength/highest frequencies of all! Produced by the hottest regions of the universe and emitted as part of nuclear fission and fusion. Uses: To kill cancer cells with local bursts.