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justwild
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In wikipedia's description of transmitter, if an alternating current is given to an antenna, then the antenna radiates off em wave.
But why this happens so?
But why this happens so?
jtbell said:The simplistic description is this:
1. An electric current produces a magnetic field.
2. An oscillating (alternating) electric current produces an oscillating magnetic field.
3. An oscillating magnetic field "produces" an oscillating electric field, which in turn "produces" more oscillating magnetic fields, which in turn "produce" more oscillating electric fields, etc. via the time-derivative terms in Maxwell's equations. These oscillations propagate at speed c.
A more accurate version of step 3 is that oscillating magnetic fields are inevitably associated with oscillating electric fields, both propagating at speed c, again via the time-derivative terms in Maxwell's equations. This avoids the implication of a circular cause and effect chain.
Neandethal00 said:Ok, oscillating electric current can produce electromagnetic waves from an antenna. Frequency of generated electromagnetic wave is the same as frequency of oscillations of current in the antenna. I think I'm correct on my last sentence.
Then I think it is also possible to observe visible light from an antenna by controlling frequency of oscillations of its current.
Just a thought.
An EM (electromagnetic) wave is a type of energy that is created when an electric field and magnetic field interact. It is a form of electromagnetic radiation and is made up of oscillating electric and magnetic fields that travel through space at the speed of light.
Emission of EM wave happens because of the interaction between electric and magnetic fields. When an electrically charged object moves or changes its speed, it creates a change in the electric field which then creates a change in the magnetic field. This creates a ripple effect, resulting in the emission of an EM wave.
Objects emit EM waves when they have an accelerating electric charge. This can happen when an object is heated, when it changes direction or speed, or when it is subjected to an external electric or magnetic field. The amount and type of EM wave emitted depends on the properties of the object and the type of acceleration it experiences.
EM waves travel through space as transverse waves, meaning that the direction of the wave is perpendicular to the direction of the oscillations of the electric and magnetic fields. They do not require a medium to travel through, unlike sound waves which require a medium of air or water. EM waves can travel through a vacuum, which is why they are able to travel through space.
There are many different types of EM waves, each with different wavelengths and frequencies. The electromagnetic spectrum includes radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays. Each type of EM wave has different properties and uses, from communication and technology to medical imaging and radiation therapy.