Electromagnetic waves how do they travel

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.

Mechanical waves and electromagnetic waves are two important ways that energy is transported in the world around us. Waves in water and sound waves in air are two examples of mechanical waves. Mechanical waves are caused by a disturbance or vibration in matter, whether solid, gas, liquid, or plasma.

Matter that waves are traveling through is called 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 next.

Sound waves cannot travel in the vacuum of space because there is no medium to transmit these mechanical waves. Electricity can be static, like the energy that can make your hair stand on end.

Magnetism can also be static, as it is in a refrigerator magnet. A changing magnetic field will induce a changing electric field and vice-versa—the two are linked. These changing fields form electromagnetic waves. Electromagnetic waves differ from mechanical waves in that they do not require a medium to propagate.

This means that electromagnetic waves can travel not only through air and solid materials, but also through the vacuum of space. In the 's and 's, a Scottish scientist named James Clerk Maxwell developed 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 now referred to as "Maxwell's Equations. Heinrich Hertz, a German physicist, applied Maxwell's theories to the production and reception of radio waves.

The unit of frequency of a radio wave -- one cycle per second -- is named the hertz, in honor of Heinrich Hertz. His experiment with radio waves solved two problems. First, 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 form of light! Second, Hertz found out how to make the electric and magnetic fields detach themselves from wires and go free as Maxwell's waves — electromagnetic waves. Light is made of discrete packets of energy called photons. Photons carry momentum, have no mass, and travel at the speed of light.

All light has both particle-like and wave-like properties. Electromagnetic waves are transverse waves. Their vibrations, or oscillations , are changes in electrical and magnetic fields at right angles to the direction of wave travel. All electromagnetic waves:. Some types of electromagnetic waves, like radio waves, microwaves, infrared waves, visible light and ultraviolet waves, can be reflected and refracted. Refraction is caused by differences in the velocity of waves travelling through different substances.

While these vibrations occur for only a very short time, they delay the motion of the wave through the medium. Once the energy of the electromagnetic wave is reemitted by an atom, it travels through a small region of space between atoms. Once it reaches the next atom, the electromagnetic wave is absorbed, transformed into electron vibrations and then reemitted as an electromagnetic wave.

This is observed in the animation below. The actual speed of an electromagnetic wave through a material medium is dependent upon the optical density of that medium. Different materials cause a different amount of delay due to the absorption and reemission process. Furthermore, different materials have their atoms more closely packed and thus the amount of distance between atoms is less. These two factors are dependent upon the nature of the material through which the electromagnetic wave is traveling.