Energy band gap of gallium arsenide phosphate is 1.98 eV.Calculate the wavelength of electromagnetic radiation emitted,when electrons and holes combine in this alloy semiconductor directly.

Calculate the photon energy in electron- volt for radiation of wavelength 1 metre.

Find the maximum wavelength of electromagnetic radiation,which can create a hole-electron pair in germanium.Given that forbidden energy gap in germanium is 0.72 eV.

Bohr model is a system consisting of small, dense nucleus surrounded by orbiting electrons. The electrons travel is defined circular orbits around the nuclues which orbital angular moementum is an integral multiple of h/(2pi) . While rotating in allowed orbits (stationary orbits) the electron does not radiate energy. electromagnetic radiations are emitted when the electron jumps from a higher orbit (E_(ni)) to a lower orbit (E_(nf)) . The total energy of the electron in an atom is negative. It suggests that