Duduli

The partition function is a fundamental quantity in statistical mechanics that describes how a system is distributed among its possible energy states. For a system in thermal equilibrium: Z = Σ e⁻ᴱⁱ/ᵏᴮᵀ where Eᵢ is the energy of the ith state, kB is the Boltzmann constant, and T is the absolute temperature. The partition function is useful because many thermodynamic quantities, such as internal energy, entropy, and Helmholtz free energy, can be calculated from it.

Proof:-

Brewster’s Law states that when unpolarized light is incident on a transparent surface at the polarizing angle i_B, the reflected and refracted rays are perpendicular to each other.       tan i_B=μ where i_B is the Brewster angle and μ is the refractive index of the medium. Key point: At Brewster angle, the reflected light is completely plane polarized.

Stars appear to twinkle because their light passes through Earth’s atmosphere. Different layers of air have different temperatures and densities, so they continuously bend the starlight in slightly different directions. Stars are extremely far away and appear as point sources of light, so these changes make their brightness seem to fluctuate. Planets are much closer and appear as tiny disks rather than point sources. Light comes from many points across the disk, and the fluctuations from different parts tend to cancel each other out.