K.E. = ½ m v v K E kg m s kg = = . . .
. / / m = m s – h m v Js . kg m s ( . )( ) = × – m = .
nm Problem . Calculate the mass of a photon with wavelength . Å. λ = .
Å = . × – m Velocity of photon = velocity of light = . × – kg h m h p v ( . ) where m is the mass of the particle, v its velocity and p its momentum.
de Broglie’s prediction was confirmed experimentally when it was found that an electron beam undergoes diffraction, a phenomenon characteristic of waves. This fact has been put to use in making an electron microscope, which is based on the wavelike behaviour of electrons just as an ordinary microscope utilises the wave nature of light. An electron microscope is a powerful tool in modern scientific research because it achieves a magnification of about million times. It needs to be noted that according to de Broglie, every object in motion has a wave character.
The wavelengths associated with ordinary objects are so short (because of their large masses) that their wave properties cannot be detected. The wavelengths associated with electrons and other subatomic particles (with very small mass) can however be detected experimentally. Results obtained from the following problems prove these points qualitatively. Problem .
What will be the wavelength of a ball of mass . kg moving with a velocity of m s – ? . .
Heisenberg’s Uncertainty Principle Werner Heisenberg a German physicist in , stated uncertainty principle which is the consequence of dual behaviour of matter and radiation. It states that it is impossible to determine simultaneously, the exact position and exact momentum (or velocity) of an electron. Mathematically, it can