The Electromagnetic Spectrum Notes 2023 PDF

The Electromagnetic Spectrum  What is it? The electromagnetic spectrum is the complete spectrum or continuum of light including radio waves, infrared, visible light, ultraviolet light, X-rays and gamma rays An electromagnetic wave consists of electric and magnetic fi...

The Electromagnetic Spectrum  What is it? The electromagnetic spectrum is the complete spectrum or continuum of light including radio waves, infrared, visible light, ultraviolet light, X-rays and gamma rays An electromagnetic wave consists of electric and magnetic fields which vibrate and transfer energy back and forth, thus making waves. Electromagnetic waves do not require matter to travel because electric fields and magnetic fields can exist where matter is not present.  Waves Properties of waves include speed, frequency and wavelength Speed (s), frequency (f) and wavelength (λ) are related in the formula λ x f = s All light travels at a speed of 300,000,000 km/s in a vacuum (186,000 mi/sec)  Wavelength, Frequency and Energy Since all light travels at the same speed, wavelength and frequency have an indirect relationship. Light with a short wavelength will have a high frequency and light with a long wavelength will have a low frequency. Light with short wavelengths has high energy and long wavelength has low energy All matter contains charged particles that are always in motion. As a result, all objects emit electromagnetic waves. Objects can emit electromagnetic waves at many wavelengths.  Dual Nature of Light Radiation carries energy and has momentum. In 1905, Albert Einstein hypothesized that light is composed of tiny particles that causes light to have both particle-like behavior and wave-like behavior. A photon is a massless bundle of energy that behaves like a particle. The photon’s energy depends on the frequency of the wave. The photon’s energy increases as the wave’s frequency increases.  Radio waves Low energy waves with long wavelengths Includes FM, AM, radar and TV waves Wavelengths of 10-1m and longer Low frequency Used in many devices such as remote control items, cell phones, wireless devices, communication, medical imaging etc. USES: Some radio waves carry an audio signal from a radio station to a radio. You hear sound when your radio changes the radio wave into a sound wave. Another use for radio waves is to find the position and movement of objects by a method called radar. Radar stands for RAdio Detecting And Ranging. It can be used for tracking the movement of aircraft, watercraft, and space-craft. MRI: called magnetic resonance imaging, uses radio waves to help diagnose illness.  Microwaves Longer than radio, shorter than light and infrared Wavelength 1 x 10 - 4 m to 1 x 10-1 m First used in radar, now used in communication, medicine and consumer use (microwave ovens)  Modulating Radio Waves © 2000 Microsoft Clip Gallery Modulation - variation of amplitude or frequency when waves are broadcast AM – amplitude modulation Carries audio for T.V. Broadcasts Longer wavelength so can bend around hills FM – frequency modulation Carries video for T.V. Broadcasts  Infrared waves Invisible electromagnetic waves that are detected as heat Every object emits infrared waves. Hotter objects emit more infrared waves than cooler objects. Can be detected with special devices such as night goggles Used in heat lamps, tv remotes Higher energy than microwaves but lower than visible light  Visible Light The portion of the electromagnetic spectrum that human eyes can detect ROY G BIV (red, orange, yellow, green, blue, indigo, violet) Red has the lowest frequency/longest wavelength and violet has the highest frequency/shortest wavelength  Ultraviolet waves Higher energy than light waves Can cause skin cancer and blindness in humans Used in tanning beds and sterilizing equipment (medical)  OZONE LAYER Humans need some sunlight to convert vitamin D into a usable form, but too much exposure is dangerous. The ozone layer is vital to life on Earth because it absorbs most of the Sun’s harmful ultraviolet waves and prevents them from reaching Earth’s surface.  X-Rays High energy waves First discovered by Roentgen Used in medicine, industry and astronomy Can cause cancer  Gamma rays Highest photon energy Blocked from Earth’s surface by atmosphere product of fission reactions can penetrate lead