Hy Do Electromagnetic Waves Not Require a Medium for Travel?
Energy, a measure of the ability to practise piece of work, comes in many forms and tin can transform from one blazon to another. Examples of stored or potential energy include batteries and water backside a dam. Objects in motion are examples of kinetic energy. Charged particles—such as electrons and protons—create electromagnetic fields when they move, and these fields transport the type of energy we call electromagnetic radiation, or light.
What are Electromagnetic and Mechanical waves?
Mechanical waves and electromagnetic waves are 2 important means that free energy is transported in the world effectually usa. Waves in h2o and sound waves in air are two examples of mechanical waves. Mechanical waves are caused by a disturbance or vibration in thing, whether solid, gas, liquid, or plasma. Matter that waves are traveling through is called a medium. H2o waves are formed by vibrations in a liquid and sound waves are formed by vibrations in a gas (air). These mechanical waves travel through a medium by causing the molecules to bump into each other, like falling dominoes transferring energy from ane to the next. Sound waves cannot travel in the vacuum of space considering there is no medium to transmit these mechanical waves.
Classical waves transfer free energy without transporting thing through the medium. Waves in a pond practice not carry the water molecules from place to place; rather the wave'south energy travels through the water, leaving the water molecules in place, much like a issues bobbing on tiptop of ripples in h2o.
When a balloon is rubbed against a caput of hair, astatic electric charge is created causing their individual hairs to repel one another. Credit: Ginger Butcher
ELECTROMAGNETIC WAVES
Electricity tin be static, like the free energy that tin make your hair stand on end. Magnetism tin can also be static, as it is in a fridge magnet. A changing magnetic field will induce a changing electric field and vice-versa—the ii are linked. These changing fields form electromagnetic waves. Electromagnetic waves differ from mechanical waves in that they do non require a medium to propagate. This means that electromagnetic waves can travel not but through air and solid materials, but also through the vacuum of space.
In the 1860'due south and 1870's, a Scottish scientist named James Clerk Maxwell adult a scientific theory to explicate electromagnetic waves. He noticed that electrical fields and magnetic fields tin couple together to form electromagnetic waves. He summarized this human relationship between electricity and magnetism into what are now referred to as "Maxwell'due south Equations."
Heinrich Hertz, a High german physicist, applied Maxwell's theories to the production and reception of radio waves. The unit of frequency of a radio wave -- i bike per second -- is named the hertz, in honor of Heinrich Hertz.
His experiment with radio waves solved two issues. Starting time, he had demonstrated in the concrete, what Maxwell had only theorized — that the velocity of radio waves was equal to the velocity of light! This proved that radio waves were a class of light! 2nd, Hertz constitute out how to make the electric and magnetic fields disassemble themselves from wires and go gratis as Maxwell's waves — electromagnetic waves.
WAVES OR PARTICLES? YES!
Light is made of detached packets of energy called photons. Photons carry momentum, take no mass, and travel at the speed of low-cal. All light has both particle-like and moving ridge-like backdrop. How an musical instrument is designed to sense the low-cal influences which of these backdrop are observed. An instrument that diffracts light into a spectrum for assay is an example of observing the wave-like property of light. The particle-similar nature of calorie-free is observed by detectors used in digital cameras—individual photons liberate electrons that are used for the detection and storage of the image data.
POLARIZATION
One of the physical backdrop of calorie-free is that it can be polarized. Polarization is a measurement of the electromagnetic field's alignment. In the figure above, the electric field (in ruby-red) is vertically polarized. Recall of a throwing a Frisbee at a sentinel fence. In ane orientation it will laissez passer through, in another it will be rejected. This is similar to how sunglasses are able to eliminate glare by arresting the polarized portion of the light.
DESCRIBING ELECTROMAGNETIC ENERGY
The terms lite, electromagnetic waves, and radiation all refer to the same physical phenomenon: electromagnetic free energy. This energy can exist described past frequency, wavelength, or energy. All three are related mathematically such that if you know one, y'all tin calculate the other two. Radio and microwaves are usually described in terms of frequency (Hertz), infrared and visible light in terms of wavelength (meters), and 10-rays and gamma rays in terms of free energy (electron volts). This is a scientific convention that allows the convenient use of units that take numbers that are neither too large nor too small.
FREQUENCY
The number of crests that pass a given betoken within one second is described as the frequency of the wave. One wave—or cycle—per second is called a Hertz (Hz), after Heinrich Hertz who established the beingness of radio waves. A moving ridge with two cycles that pass a point in one second has a frequency of two Hz.
WAVELENGTH
Electromagnetic waves have crests and troughs similar to those of bounding main waves. The distance betwixt crests is the wavelength. The shortest wavelengths are just fractions of the size of an atom, while the longest wavelengths scientists currently study can be larger than the diameter of our planet!
Free energy
An electromagnetic wave can likewise be described in terms of its energy—in units of measure chosen electron volts (eV). An electron volt is the amount of kinetic energy needed to move an electron through one volt potential. Moving forth the spectrum from long to short wavelengths, energy increases every bit the wavelength shortens. Consider a jump rope with its ends being pulled upwards and down. More than energy is needed to make the rope have more waves.
Superlative of Folio | Adjacent: Wave Behaviors
Citation
APA
National Aeronautics and Space Assistants, Science Mission Directorate. (2010). Anatomy of an Electromagnetic Wave. Retrieved [insert date - due east.g. August x, 2016], from NASA Science website: http://science.nasa.gov/european monetary system/02_anatomy
MLA
Scientific discipline Mission Advisers. "Anatomy of an Electromagnetic Wave" NASA Science. 2010. National Aeronautics and Space Administration. [insert date - due east.thou. 10 Aug. 2016] http://science.nasa.gov/ems/02_anatomy
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