Electromagnetic Spectrum Applications

Electromagnetic Spectrum Applications

• Electromagnetic waves travel at the speed of light (300,000,000 meters/second) in a vacuum.
• Waves have different wavelengths and frequencies.
• Longer wavelengths have lower frequencies, and shorter wavelengths have higher frequencies.
• Higher frequency = higher energy
• Radio waves have the longest wavelengths and lowest frequencies of all electromagnetic waves.
• Radio waves are used in global positioning systems (GPS).
• GPS measures the time a radio wave takes to travel to a receiver to determine distances.
• A radio picks up radio waves, converts them to sound waves, and broadcasts at specific frequencies.
• The number on a radio dial indicates the frequency.
• Audio-frequency (AF) signals are patterns of varying electric current.
• Radio-frequency (RF) is high-frequency radio.
• Frequency modulation (FM) changes the frequency of a wave to match a signal.
• MRI (Magnetic Resonance Imaging) uses short radio waves with a magnet to create images.
• Microwaves have shorter wavelengths and higher frequencies than radio waves.
• Microwaves are used in microwave ovens to transfer energy to water molecules in food, causing vibrations and heat transfer.
• Another application for microwaves is radar (Radio Detection and Ranging).
• Radar uses electromagnetic sensors to detect, locate, track, and recognize objects at a distance.
• Terrestrial communications use microwaves, like satellite television and cell phones.
• Infrared rays lie beyond the visible light spectrum.
• Objects emit infrared rays based on their temperature.
• Thermograms use infrared radiation to show regions of different temperatures (e.g., in the human body).
• Heat lamps emit infrared waves.
• Infrared photographs show details of vegetation on Earth.
• Infrared scanners show temperature variations in the body.
• Infrared remote controls use infrared waves.
• Infrared night vision goggles use infrared rays.
• Autofocus cameras use infrared to aid focusing.
• Visible light has a shorter wavelength and higher frequency than infrared rays.
• Visible light is the electromagnetic radiation we can see, with red light being the longest wavelength and violet light being the shortest.
• When light enters a new medium, it bends (refracts). Different wavelengths refract by different amounts, separating white light into various colors.
• Ultraviolet (UV) rays have shorter wavelengths and higher frequencies than visible light and carry more energy.
• UV lamps are used in banks to check signatures on passbooks.
• UV radiation is used to sterilize water from drinking fountains.
• Sunlight produces vitamin D in the skin, leading to a tanning effect.
• Too much UV radiation can cause skin cancer.
• Sunscreen protects the skin from UV radiation.
• X-rays have shorter wavelengths and higher frequencies than UV rays, carrying a great amount of energy and penetrating most matter.
• X-rays are produced when fast-moving electrons hit a metal target.
• Wilhelm Conrad Roentgen discovered X-rays.
• Bones and teeth absorb X-rays.
• X-ray machines use X-rays for imaging various structures and diagnosing conditions.
• X-rays can also be used by engineers to detect small cracks in structures.
• Gamma rays have the shortest wavelengths and highest frequencies, carrying the greatest amount of energy and penetrating the most matter.
• Gamma rays are used in radiotherapy to treat cancer cells.
• Exploding nuclear weapons release gamma rays.
• The Hulk (from the comics) was created by exposure to gamma radiation.