# Electromagnetic Waves

## What is the difference between Mechanical and Electromagnetic waves?

Electromagnetic waves are different from Mechanical waves because of the medium they travel through. Electromagnetic waves can travel through a vaccum, or an area where there is no matter (i.e outer space) while Mechanical waves need matter to travel through, such as water, air, or a solid like stone or dirt

## How are Electromagnetic waves produced?

Electromagnetic waves are formed when a charged particle creates an electric field. This field exerts a force on other charged particles, causing them to accelerate, with the positively charged particles heading in the direction of the field while the negatively charged ones head away from the field. The moving charged particles produce a magnetic field, which also exerts a force on the moving particles and changes the direction of their velocity. These two fields combine to form an Electromagnetic wave. The produced electromagnetic waves travel through space at the speed of light (electromagnetic waves are light waves)

## The Electromagnetic Spectrum

Electro magnetic waves have a huge range of frequencies. These frequencies are known as the electromagnetic spectrum. This spectrum's different variations is identified in regions. These regions are (from lowest frequencies to highest) radio waves, microwaves, infared waves, visible light waves, ultraviolet rays, x-rays, and gamma rays.
Electromagnetic waves and the electromagnetic spectrum | Physics | Khan Academy

Radio waves have the longest wavelengths and lowest frequencies, so they are not visible to the human eye. In nature, they are produced by celestial bodies like stars and gases. Their use in our world is for transmitting and recieving messages, recieving songs in a car radio, using radio telescopes.

## Microwaves

Microwaves have the second longest wavelengths and their frequencies are slight higher than radio waves. Microwaves are distinguished into different bands. Medium length (C-band) microwaves are used to penetrate through clouds, dust, smoke, rain, and snow to show the surface of the Earth. L-band microwaves are used in GPS's and also can be used to measeure the soil moisture of forests by penetrating the canopy.

## Infrared Waves

Infared light is at a slightly lower frequency than visible light, and their wavelengths are just a bit longer. Infared waves are divided into near-infared, mid-infared, and far-infared. The complete region is often known as thermal infared, because it is primarily used by scientists to study the long range thermal radiation being emmitted by our planet. Some other uses are also for tv remotes, Infared lams, wich heat rooms, and examining wildfires to find the strongest spots of the fire.

## Visible Light

Visible light is all waves with a wavelength between 700 nm (nano meters) and 400 nm. They also have a higher frequency than Infared waves. As the name suggests, visible light is the region of the electromagnetic spectrum that we can see. Each color has a varying frequency and wavelength. When all combined, visible light looks white. Diffracting it, however, causes all the wavelengths to seperate, allowing you to see the different colors. Visible light is used to light our homes and can also create brilliant patterns when certain light waves are allowed down certain paths.

## Ultraviolet

Ultraviolet light has a shorter wavelength and higher frequency than visible light, which is why it is invisible to the naked eye. Some organisms like bees, however, because their eyes are specially adapted to do so. The sun produces the full spectrum of ultraviolet radiation, which includes UV-C rays, which are extremely harmful and vrtually all of them are absorbed into the atmosphere, UV-B rays, which cause sunburns, and UV-A, which accounts for about 95% of all the UV rays reaching the earth without being absorbed into the atmosphere. Scientists can use satelites to study the UV rays, and in turn young stars, because most of the light they emit is Ultraviolet light. Scientists can also use it to study parts of space where visible light doesn't reach, such as craters located in permanent darkess on the far side of the moon.

## X-rays

X-rays have much higher frequency and energy, as well as much shorter wavelengths than ultraviolet light. Scientists will more often define X-rays by their energy levels than their wavelengths. These X-rays have a wavelength between 0.03 and 3 nanometers, meaning that many are only about the size of an atom. X-rays are typically used to show skeletal structures in humans and other vertebrates, though they are also used to reveal white dwarf stars, neutron stars, and black holes in space.

## Gamma Rays

Gamma waves have the shortest wavelengths and the highest frequency in the electromagnetic spectrum. They are produced by the hottest and most energetic celestial bodies, such as pulsars and neutron stars. Gamma rays are extremely energetic and can travel long distances. Scientists use them to study the types of elements on other planets, as well as study the different celestial bodies and the paths they take, such as black holes, which produce gamma rays from their accretion disks.