Can u guys explain me wat a uv catastrophe is....and what is its relation with max plank's quantum theory

In thermodynamics there is a concept called equipartition of energy — all modes of motion in an oscillator will get equal amounts of energy when in equilibrium. So something that can vibrate back and forth, which has one degree of freedom, will have some energy: 1/2 kT. Something moving in 2D will have kT and something in 3D will have 3/2 kT. Add in rotation, and you get up to 3 more modes.

 

But a cavity, which has oscillator-like modes, comprised of standing waves of EM radiation, can't follow this. Most of the modes are at short wavelengths, and the energy goes up as the wavelength decreases. As you get into the UV, the predicted radiated power from the modes gets really large, and the classical prediction (from the Rayleigh–Jeans law) breaks down. The rules don't work, i.e. you have a catastrophic failure — a prediction of radiating far more energy than the system actually has.

 

Planck fixed the problem.

 

http://en.wikipedia.org/wiki/Ultraviolet_catastrophe