ELECTROMAGNETIC WAVE
Currently almost all people have the equipment on this one. He was so small that can be placed comfortably in a pocket, but is considered to have a very large function primarily to communicate. Yes, it is a mobile phone (cellular phone). Currently mobile phones are not only used to call it but also for other functions such as send and receive short messages (SMS), listen to music or take photographs. How mobile devices can connect with other mobile devices when they are far from each other?
Concepts that can explain this phenomenon is the concept of electromagnetic waves. And, the concept proved a very broad electromagnetic wave does not only relate to a TV or phone only, but many other applications that can often be found daily around us. Applications include microwave, radio, radar, or x-rays.
As we discussed earlier that there are two basic laws that connects electricity and magnetism symptoms.
First, electric currents can be produced (induced) magnetic field. This phenomenon is known as magnetic induction. The foundation stone of this concept is that Oersted had discovered this phenomenon experimentally and formulated in full by Ampere. Symptoms of magnetic induction is known as Ampere's law.
From these two basic principles of electrical magnets above and taking into account the prevailing concept of symmetry in the laws of nature, James Clerk Maxwell submitted a proposal. Maxwell put forward the proposal, namely that if the magnetic field varies with time can produce an electric field then it might otherwise occur. Thus Maxwell suggested that the electric field varies with time can produce (induced) magnetic field. Maxwell's proposal was later to become the third law that links between electricity and magnetism.
So the third principle is the electric field changing with time can produce a magnetic field. This third principle proposed by Maxwell is a development of the formulation of Ampere's law. Therefore, this principle is known as Ampere-Maxwell Law.
Of the three basic principles of electricity and magnetism at the top, Maxwell saw the existence of a basic pattern. The magnetic field can generate time-varying electric fields that also vary with time, and the electric field varies with time can also generate magnetic fields. If this process is continuous it will produce a magnetic field and electric field are continuous. If the magnetic field and electric field simultaneously propagate (spread) in all directions in space then this is a wave phenomenon. Such waves are called electromagnetic waves because it consists of electric and magnetic fields that propagate in space.
Maxwell's prediction of electromagnetic waves was actually proven. Was Heinrich Hertz who proved the existence of electromagnetic waves through his experiments. Hertz experiment itself in the form of electromagnetic wave generation from an electric dipole (two poles electrically charged with different charges, the adjacent positive and negative) as an electric dipole transmitter and another as a receiver. Transmitter and receiver antennas are currently using a principle like this.
