20 Topics.
0 of 4 Concepts Done
Asked in UPSC PrelimsUPSC 2002UPSC 2008
What to Study: Understand what an electromagnetic wave is made of and why it is called transverse. Why does it need no medium, unlike a mechanical wave? How are wavelength, frequency and energy related? Remember the wave behaviours it shows (reflection, refraction, diffraction, polarisation) and the photon idea.
Asked in UPSC PrelimsUPSC 2008UPSC 2009
What to Study: Remember the seven bands in order, from radio waves to gamma rays, with a rough sense of their wavelengths. Along this order, which way do frequency, wavelength and energy change? At about which wavelength, and in which band, is the Sun's radiation most intense?
Asked in UPSC PrelimsUPSC 2009UPSC 2010
What to Study: For each band, does it reach the ground through the atmosphere, or is it absorbed (and by what)? Remember the main uses of each band. Why can radio and visible-light telescopes work from the ground, while X-ray astronomy needs to go to space?
What to Study: How are radio frequencies grouped into named bands (VHF, UHF, SHF, EHF)? Know which bands mobile services, Wi-Fi and satellites use. Understand spectrum as a scarce public resource, and how the Telecommunications Act, 2023 provides for auction and for administrative assignment. Why is this choice contested for satellite services?