wave propagation

Normally in the conductor free electrons are present due to which we have electric fields and if these are moving we also have the magnetic fields around the conductor. These electric and magnetic fields are responsible for the wave to propagate.normally we observe it in the case of antenna propagation,when antenna is fed by the current source due to charge and as this charge is flowing we have electric and magnetic fields which help in wave propagation.we have many types of antenna's in the past like yagi-uda antenna which has a dipole for which the current is fed,in this antenna another two parasitic elements are present called directors and reflectors. reflector is used to reflect back the back side radiation(opposite to the wave propagation) directors are used to place the radiation in the desired direction.we also have reflector antennas,horn antenna,microstrip antenna(mostly used in mobile phones),helical antenna and many more designing up.But the principle remains same.
The antenna height is determined by the wave frequency.if the wave is of smaller frequency it requires very long antenna(since wavelength is inversly proportional to frequency) and if the wave has higher frequency we can easily transmit,but due to tech development we developed some modulation techniques to transmit the wave having lower frequency.
Suppose assume that wave is propagating along x-axis,then we have the electric and magnetic fields in perpendicular direction to x-axis that is it may be along y or z-axes.In the direction of propagation we dont have any types of fields.further if electric field is along is y-axis,it will be independent of 'y' but is a function of 'x'.similarly if magnetic field is along z-axis,it will be independent of 'z' but will be function of 'x'.
 Based on the maxwell's equations we can decide the nature of wave in the charge ,free and conducting region.The nature of the EM waves vary from medium to medium and also upon the angle of incidence whether it is oblique or normal incidence.

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End of world

Now a days we may hearing the word about how the world is going to be destroyed. There are so many ways but i think these are only few that we should fear.
1.water :our planet earth consists of 75 percent of water and 25 percent of land . So we should think the major one is going to affect the minor in which we are leading the life. Among this most of the impure water is present in oceans and seas and the minimum quantity of pure water is present as ice caps. The land near to these would think that they are in danger because the water is melting due to this the land will get destroy. So that every individual should take part in controlling the global warming.
2.Earthquakes:now a days we are watching in our tv's that so many people are dying due to earthquakes . These days it is common the earthquake is occured at this place and at another place . We have device to estimate the amount of earthquake occured but we dont have the machines to discover it first. Animals are able to discover but man could not. So now there is a need to discover the machine and to minimise the destroy.
3.valcones:Due to this the region around is being damaged. Normally the region is forest . If forest gets destroy the equilibrium will be damaged so that at last man suffers. So we should careful in controlling this.
4.brimstone and fire from heaven:The fire coming from the heaven is the major possibility the our living planet will get destroy. This brimstone normally contains 98 percent of sulphur . The amount of damage we can see in the holy bible which is happened in the city called sodom. So the man should learn from this.
>conclusion:If we want to survive in the we should be in control of this four ways and we should search a way in protecting the beautiful planet earth.

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