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Give the brief history of discovery of knowledge of electromagnetic waves. |
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Answer» Solution : Faraday from his experimental study of electromagnetic induction magnetic field changing with time, gives rise to an electric field. ii) Maxwell in 1865 from his theoritical study CONCLUDED that, an electric field changing with time gives rise to magnetic field. iii) It is a consequence of the displacement current being a source of magnetic field. iv) It means a CHANGE in electric (or) magnetic field with time produces the other field. v) Maxwell concluded that the variation in electric and magnetic field vectors perpendicular to each other leads to the production of electromagnetic waves in space. vi) These electromagnetic waves travel in space without any material medium. vii) Both electric and magnetic fields vary with time and space and have the same frequency.  viii) The electric field vector `vec E` and magnetic field vector `vecB` are vibrating along y and z axis and propagation of electromagnetic waves along x- axis. ix) Maxwell found that the electromagnetic waves travel in vacuum with a speed is GIVEN by `C=(1)/(sqrt(mu_(0)epsi_(0)))=3xx10^(8)` m/s Where `mu_(0)=4pixx10^(-7)` H/m=permeability in free space. `epsi_(0)=8.85xx 10^(-2) c^(2)N^(-1) m^(-2)`=permittivity in free space. x) The velocity of electromagnetic waves in a medium is given by `v=(1)/(sqrt(muepsi))`. xi) Maxwell also concluded that electromagnetic waves are transverse in nature. xii) In 1988 Hertz demonstrated experimentally the production and detection of E.M waves using spark oscillator. XIII) In 1895 Jagadish Chandra Bose was able to produce E.M waves of wavelength 5m.m to25 m.m. xiv) 1899 Marconi was the first to establish a wireless communication at a distance of about 50 km. |
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