REACT 2018, SRM University, Chennai, 6.4.2018; National Level Technical Symposium, EPULZ 2K18, Thanthai Periyar Government Institute of Technology, Vellore, 14.3.2018.
James Clerk Maxwell, using his famous Maxwell’s equations, predicted the existence of invisible electromagnetic waves in 1865, and Heinrich Hertz became the first to demonstrate the existence of such waves in 1887 by building an apparatus that produced and detected microwaves in the ultra-high frequency region. The electromagnetic spectrum spans from longest wavelength to shortest: radio waves, microwaves, infrared, optical, ultraviolet, x-ray, and gamma-rays– has developed the comforts and pleasures of 21st century life. By 1900, Tesla proposed that radio waves could detect objects, and radar was born. The onset of two world wars pushed the strategic needs to higher frequencies and higher power levels as the lower frequency regions of the electromagnetic spectrum were congested. This motivated the quest for still higher powers and frequencies. Not only for military applications, but also commercial and space applications these waves have played a part. NASA’s Spitzer space telescope observed the presence of water and organic molecules in a galaxy 3.2 billion light-years away. Viewing our sun in multiple wavelengths in SOHO satellite allows scientists to study and understand sunspots that are associated with solar flares and eruptions harmful to satellites, astronauts and communications here on earth.