# Why is light electromagnetic wave?

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Why do people say light, radio, microwave, Infrared and gamma waves so on are electromagnetic waves?

What are electromagnetic waves? And why is light or radio so on electromagnetic? Why do light waves or radio waves have no mass and cannot be measured?

In: 2

1. I really want to see someone more knowledgeable than me answer this one.

2. I feel like the measurement of light waves and radio waves is fairly precise.

Answer: Electro magnetic waves are waves in the electro/magnetic field, much like water waves are waves in water.
Electromagnetic waves can vibrate fast or slow, like some big water waves use a long time rolling in on a beach while smaller waves hits more often.
We have given different frequencies in the e/m field different names, because different frequencies interact with stuff in different ways. Radio waves are long waves, but the can easily move through walls. Visible light is shorter waves, but cannot move through most walls, except things like glass.

A radio transmitter is basically just a lamp, but it emmits long waves that our eyes cannot see, but a radio can.

Some animals see more electromagnetic waves with their eyes than humans, and if they could speak they would talk about colors that we cannot even imagine.

Measuring e/m waves is pretty easy, since an e/m field will try to move any magnetic or an electric particle caught in the field. Thats how our eyes see, or a radio plays music.

Many forces in the universe have no mass. They are not physical in that sense. They are waves of fields that move through the universe. An E/m wave can sometimes look like it is one small object, because there is a lower, minimum amount of energy a wave can have, this wave cannot be split in two. We call this minimum packet of e/m a photon.

Electromagnetic waves are a solution of the Maxwell equations. Since the electric field and magnetic field can create each other if you solve the equations for vacuum and a specific geometry where the magnetic and electric filed components are perpendicular, you get a wave equation. The solution is a wave where the electric and magnetic filess are always perpendicular and they travel with the speed of light.

Later Herts showed that these electromagnetic waves did exist and visible light is one range of frequencies.

Now a wave is just how energy moves in a medium. When it comes to the EM field what happens is that lets say a charge accelerates. You got a changing electric field creating a changing magnetic field which creates a changing electric filed and so on. Its a wave. Why doesn’t it have mass? A wave doesn’t have mass, you could say that a wave has mass if it consists of particles like a wave on a string but you wouldn’t really say its the wave that has mass.

An electromagnetic wave is, to be *super* reductive, energy. If you imagine a field of static electromagnetism to be like a pond, an electromagnetic wave travels along this field in the same way a wave would travel across the water of a pond.

These waves are usually caused by something, like the movement of matter, creating an imbalance that causes a ripple, like throwing a stone in a pond.

We classify these waves by their oscillating frequency. At the low end it’s radio waves, at the high end it’s gamma waves. Visible light sits somewhere in the middle.

Energy isn’t matter, so you can’t weigh it. You can measure how hot something is by temperature, but the weighing scale doesn’t tell you how hot it is.

But you CAN measure the amplitude of an electromagnetic wave, the wave length, the frequency and the intensity.

They are called electromagnetic waves because a light wave is made of a magnetic field which creates an electric field when it collapses, which creates a magnetic field when it collapses, etc.

They can be measured, you can use an antenna and radio to listen to information embedded in radio waves, you can measure the frequency (how quickly it goes from electric to magnetic) and its amplitude (how big the electric fields and magnetic fields are), we can measure its polarisation (the angle of the wave) and its phase (when the electrical fields are strongest as opposed to a when they are strongest in a reference wave)