– . However commonly used unit is cm – (not SI unit). Problem . The Vividh Bharati station of All India Radio, Delhi, broadcasts on a frequency of , kHz (kilo hertz).
Calculate the wavelength of the electromagnetic radiation emitted by transmitter. Which part of the electromagnetic spectrum does it belong to? The wavelength, λ , is equal to c/ ν , where c is the speed of electromagnetic radiation in vacuum and ν is the frequency. Substituting the given values, we have c v This is a characteristic radiowave wavelength.
Problem . The wavelength range of the visible spectrum extends from violet ( nm) to red ( nm). Express these wavelengths in frequencies (Hz). (1nm = – m) Using equation .
, frequency of violet light = . × Hz * Diffraction is the bending of wave around an obstacle. ** Interference is the combination of two waves of the same or different frequencies to give a wave whose distribution at each point in space is the algebraic or vector sum of disturbances at that point resulting from each interfering wave. Frequency of red light ν = = .
× Hz The range of visible spectrum is from . × to . × Hz in terms of frequency units. Problem .
Calculate (a) wavenumber and (b) frequency of yellow radiation having wavelength Å. (a) Calculation of wavenumber ( ) λ =5800Å = × – cm = × – m (b) Calculation of the frequency ( ν ) . . Particle Nature of Electromagnetic Radiation: Planck’s Quantum Theory Some of the experimental phenomenon such as diffraction * and interference ** can be explained by the wave nature of the electromagnetic radiation.
However, following are some of the observations which could not be explained with the help of even the electromagentic theory of 19th century physics (known as classical physics): (i) the nature of emission of radiation from hot bodies (black-body radiation) (ii) ejection of electrons from metal surface when radiation strikes it (photoelectric effect) (iii) variation of