How Do Electromagnetic Waves Travel Through a Vacuum and a Medium
Free energy, a measure of the power to do work, comes in many forms and tin transform from i type to another. Examples of stored or potential energy include batteries and water backside a dam. Objects in move are examples of kinetic free 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 of import ways that energy is transported in the world around us. Waves in h2o and sound waves in air are 2 examples of mechanical waves. Mechanical waves are caused past a disturbance or vibration in matter, whether solid, gas, liquid, or plasma. Matter that waves are traveling through is chosen a medium. Water 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 one to the side by side. Sound waves cannot travel in the vacuum of space because at that place is no medium to transmit these mechanical waves.
Classical waves transfer energy without transporting matter through the medium. Waves in a pond practise not acquit the h2o molecules from identify to identify; rather the wave's energy travels through the h2o, leaving the h2o molecules in identify, much like a bug bobbing on top of ripples in h2o.
When a balloon is rubbed confronting a head of hair, astatic electric charge is created causing their individual hairs to repel one another. Credit: Ginger Butcher
ELECTROMAGNETIC WAVES
Electricity can exist static, similar the energy that tin make your hair stand on stop. Magnetism can also exist static, equally it is in a refrigerator magnet. A changing magnetic field volition induce a irresolute electric field and vice-versa—the two are linked. These changing fields form electromagnetic waves. Electromagnetic waves differ from mechanical waves in that they exercise not require a medium to propagate. This means that electromagnetic waves can travel not only through air and solid materials, merely also through the vacuum of space.
In the 1860'due south and 1870'south, a Scottish scientist named James Clerk Maxwell adult a scientific theory to explain electromagnetic waves. He noticed that electrical fields and magnetic fields can couple together to form electromagnetic waves. He summarized this relationship between electricity and magnetism into what are at present referred to as "Maxwell's Equations."
Heinrich Hertz, a German language physicist, applied Maxwell'due south theories to the production and reception of radio waves. The unit of frequency of a radio wave -- one bike per second -- is named the hertz, in honour of Heinrich Hertz.
His experiment with radio waves solved two problems. First, he had demonstrated in the physical, what Maxwell had only theorized — that the velocity of radio waves was equal to the velocity of calorie-free! This proved that radio waves were a class of light! Second, Hertz found out how to make the electric and magnetic fields detach themselves from wires and go costless as Maxwell'due south waves — electromagnetic waves.
WAVES OR PARTICLES? Yes!
Lite is made of discrete packets of energy chosen photons. Photons bear momentum, have no mass, and travel at the speed of light. All calorie-free has both particle-similar and wave-similar properties. How an instrument is designed to sense the calorie-free 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 lite. The particle-similar nature of light is observed past detectors used in digital cameras—individual photons liberate electrons that are used for the detection and storage of the image data.
POLARIZATION
I of the physical properties of lite is that it can be polarized. Polarization is a measurement of the electromagnetic field's alignment. In the figure in a higher place, the electric field (in red) is vertically polarized. Retrieve of a throwing a Frisbee at a lookout debate. In 1 orientation it volition laissez passer through, in another it volition be rejected. This is like to how sunglasses are able to eliminate glare by absorbing the polarized portion of the lite.
DESCRIBING ELECTROMAGNETIC ENERGY
The terms light, electromagnetic waves, and radiation all refer to the same physical miracle: electromagnetic energy. This energy can exist described by frequency, wavelength, or free energy. All three are related mathematically such that if you know i, you can calculate the other ii. 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 energy (electron volts). This is a scientific convention that allows the user-friendly employ of units that have numbers that are neither besides large nor also small.
FREQUENCY
The number of crests that laissez passer a given indicate within one second is described as the frequency of the wave. I wave—or cycle—per second is called a Hertz (Hz), later on Heinrich Hertz who established the existence of radio waves. A wave with ii cycles that pass a point in one second has a frequency of 2 Hz.
WAVELENGTH
Electromagnetic waves accept crests and troughs similar to those of ocean waves. The altitude between crests is the wavelength. The shortest wavelengths are but fractions of the size of an cantlet, while the longest wavelengths scientists currently report can exist larger than the diameter of our planet!
ENERGY
An electromagnetic moving ridge can also be described in terms of its energy—in units of measure called electron volts (eV). An electron volt is the amount of kinetic free energy needed to move an electron through ane volt potential. Moving along the spectrum from long to short wavelengths, energy increases equally the wavelength shortens. Consider a spring rope with its ends being pulled upward and down. More than energy is needed to make the rope have more waves.
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Citation
APA
National Helmsmanship and Infinite Administration, Science Mission Directorate. (2010). Beefcake of an Electromagnetic Moving ridge. Retrieved [insert date - east.g. August 10, 2016], from NASA Science website: http://scientific discipline.nasa.gov/ems/02_anatomy
MLA
Scientific discipline Mission Advisers. "Anatomy of an Electromagnetic Moving ridge" NASA Scientific discipline. 2010. National Aeronautics and Space Administration. [insert appointment - e.g. 10 Aug. 2016] http://science.nasa.gov/ems/02_anatomy
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