Symmetry in Physical Laws

‘Symmetry’ has a special meaning in physics. A picture is said to be symmetrical if one side is somehow the same as the other side. Precisely, a thing is symmetrical if one can subject it to a certain operation and it appears exactly the same after the operation. For example, if we look at a base that is left and…

Statistical Physics: Macrostates and Microstates

Consider some (4, say) distinguishable particles. If we wish to distribute them into two exactly similar compartments in an open box, then the priori probability for a particle of going into any one of the compartments will exactly 1/2 as both compartments are identical. If the four particles are named as a , b, c and d and the compartments…

Statistical Physics: Ensembles

Ensembles As a system is defined by the collection of a large number of particles, so the “ensembles” can be defined as a collection of a number macroscopically identical but essentially independent systems. Here the term macroscopically independent means, as, each of the systems constituting an ensemble satisfies the same macroscopic conditions, like Volume, Energy, Pressure, Temperature and Total number…

Rayleigh- Jean’s Law

Lord Rayleigh on classical limes made an attempt to explain the energy distribution in black body radiation, which was completed by Jeans in 1900. The result obtained by then is known as Rayleigh – Jean’s Law. Black body emits radiation of continuously variable wavelength right from zero to infinity. This radiation can be imagined as broken up into monochromatic waves.…

Wein’s Formula & Wein’s Laws

Various workers tried to explain the problem of energy distribution in black body radiation and finally the problem was successfully solved by German Physicist Max Planck. Before him, German Physicist Wilhelm Wein and British Physicist Lord Rayleigh & James Jean have tackled this problem and have given important laws. In fact, the work of their scientists paved the way for…

Entropy and Disorder

In science, we look for patterns to discover nature’s laws. What is the pattern common to all spontaneous changes? To find a pattern, it is often best to start with very simple examples, because then the pattern is likely to be more obvious. So let’s think about two simple spontaneous changes — the cooling of a hot metal and the…