in this video we're going to talk about electromagnetic waves what are electromagnetic waves well for starters they're waves and what is a wave a wave is a disturbance that can carry energy from one place to another so here's an example of a wave like all waves electromagnetic waves they have amplitude they have wavelength and also frequency electromagnetic waves they propagate at the speed of light which is 3 times 10 to the 8 meters per second this speed is equal to the wavelength of the wave times the frequency so when the wavelength decreases the frequency of the wave increases the frequency is inversely related to the period of a wave the period is the time it takes for the wave to complete one cycle the frequency is the number of cycles that it can make in one second the unit of frequency is the hertz and for period it's in seconds the energy of an electromagnetic wave is equal to planck's constant times the frequency planck's constant is 6.626 times 10 to the negative 34 joules times seconds now there's a lot of different types of waves in nature think of an ocean wave you know it has a crest it has a trough think of a wave on a string but an electromagnetic wave is different this type of wave is composed of electric and magnetic fields thus we have the name electromagnetic waves and let's draw it so we're going to draw a 3d coordinate system my drawing is not perfect but i'm going to make the best of it so first let's draw the electric field component of an em wave the electric field oscillates up and down we'll call this axis time now when the electric field is changing it will create a change in magnetic field and the change in magnetic field in turn will create a change in electric field and so when you're dealing with an em wave you have an electric field on y axis and perpendicular to it you have a magnetic field we'll call it b so that is an electromagnetic wave on one axis you have the electric field which are oscillating and on another axis perpendicular to it you have oscillating magnetic fields the electric field is equal to the speed of light times the strength of the magnetic field electromagnetic waves can be created by any type of charged particle a charged particle always has an electric field around it a moving charge particle can create a magnetic field but an accelerating charged particle can create a propagating electromagnetic wave here's another example so let's say we have a hydrogen atom and let's say that this is the first energy level this one's the second and let's say this is the third energy level let's say we have an electron an excited electron in a third energy level when the electron drops from the third energy level to the second energy level or even lower than that anytime it goes from a high energy level to a low energy level it can emit an electromagnetic wave sometimes it can emit a photon of light now for the hydrogen atom the energy of the photon that's emitted is equal to negative 2.18 times 10 to the negative 18 joules times 1 over n final squared minus 1 over n initial squared where n is the energy level of the electron this is the initial energy level in this case that will be n equal 3 this is the final energy level that's where it's going to and equal to when an electron absorbs a photon it can jump from a low energy state to a high energy state but when it falls from a high energy state to a low energy state it can release a photon in the form of an electromagnetic wave but not only that though when electrons are oscillating within a metal they can also emit electromagnetic waves even when they're heated if you were to heat up metal to a very high temperature eventually the metal will appear in red hot at this point it's emitting infrared radiation and even red light as well as you raise the temperature it'll produce light through incandescence it'll appear yellow and if you raise it even further it'll appear bright white so when the temperature is high the atoms are oscillating the electrons oscillating and they're emitting electromagnetic waves so anytime a charged particle is experiencing acceleration whether it's moving from a high energy state to a low energy state or if it's oscillating it can emit an em wave