unlocked puzzles of science

    Wave-Particle Duality One of the major phenomenon that can't be explained by classical mechanics is the wave-particle duality. Light waves act like particles and particles act like waves.           Fig: Wave-Particle duality Particle nature of light explains photoelectric effect and black body radiation. Wave nature of light explains the phenomenon of interference and diffraction.  Wave-particle duality is the ability of a matter to behave as a wave or particle.  The Schrodinger equation  determines the allowed wave functions for the system and how they evolve over time. A wave function behaves qualitatively like other waves such as water waves and waves on a string, because the Schrodinger equation is mathematically a type of wave equation. This explains the name 'wave function'  and gives rise to the wave -particle duality.  The wave of the wave function is not a wave in physical state, it is a wave in an abstract mathematical "space"  and in this respect

  Wave nature of Electromagnetic Radiations Maxwell , in 1873 , showed theoretically that an oscillating electrical circuit should radiate electromagnetic waves propagating with the velocity of light.  The main features of this theory are : 1 .  Energy may be emitted from any source such as heated rod or filament of a bulb through which electric current is passed. Energy is emitted continuously in the form of radiations (waves).  2.  These waves are associated with oscillating electric field and magnetic field. These two fields are perpendicular to each other and perpendicular to the direction of propagation of the radiation as shown in the figure.  Fig: Oscillating electric and magnetic fields emitted by charged particles.  3.  The radiations possess wave nature. Their velocity is equal to the velocity of light, i.e, 3×10⁸ m/sec. The radiations are called electromagnetic radiations or electromagnetic waves.  4. Electromagnetic waves do not require any material medium for propagation.

 Particle nature of radiation (Or light)  Electromagnetic wave theory explains the properties of light such as interference , diffraction and polarization . But certain phenomena like photoelectric effect, black body radiation, line spectra of atoms with special reference to hydrogen, variation of heat capacity of solids as a function of temperature, could only be explained by quantum (photon) theory of radiation in which radiation is considered as a particle nature.   It means that radiation has a dual nature, both as a particle and as a wave. By taking an example it could be easier to explain.  Example:  when we see an object, both the aspects are important. The gathering and focusing of light by the eye-lens is well described by the wave picture, while absorption of light by the retina is described by the photon picture of light.  In 1901,Planck put forward the particle nature of electromagnetic radiations(Planck's Quantum Theory)  to explain the phenomenon of black body radiati