Osm Physics by Ashish

  In 1947, Dennis Gabor invented a new interferometric technique that records both the amplitude (intensity) and the phase of the light waves. This technique is called holography , and the recorded interference pattern on a transparent photographic plate is called a hologram . The word “holography” comes from the Greek words holo (complete) and gramma (writing). Principle of Holography In holography, a highly coherent laser beam is split into two beams of appropriate intensity: the object beam and the reference beam . The object beam illuminates the object. The light scattered by the object interferes with the reference beam. The resulting interference pattern is recorded on a transparent photographic plate. Holography is thus a two-stage process: Construction (recording) of the hologram – formation of the interference pattern. Reconstruction of the image – the hologram acts as a diffraction grating and produces the image when illuminated by a suitable reference beam. Construc...

  If heat is transferred from system A to system A′ (the surroundings) and the temperature of A′ remains unchanged, then system A′ is called a heat reservoir. Let system A be in its i-th state with energy Eᵢ. The combined system A*, consisting of A and A′, is completely isolated. Therefore, its total energy E* remains constant. Hence, when the energy of system A is Eᵢ, the energy of the reservoir A′ is E′ = E* − Eᵢ.    (1) According to the principle of a priori probabilities, all accessible microscopic states of an isolated system are equally probable. Therefore, the probability Pᵢ of finding system A in its specific i-th state is directly proportional to the number of accessible states of the reservoir: Pᵢ ∝ Ω′(E′). Thus, Pᵢ = C′Ω′(E′), or, using Eq. (1), Pᵢ = C′Ω′(E* − Eᵢ).    (2) where C′ is a proportionality constant independent of the i-th state. Since system A is very small compared with the heat reservoir A′, Eᵢ ≪ E*, and therefore E′ ≈ E*. The ...

Motion Relative to Earth (Rotating Frame) Earth is a non-inertial (rotating) frame , so we add fictitious forces to apply Newton's laws. 1. Centrifugal Force (affects g ) Cause: Earth's rotation (every object, moving or not). Direction: Radially outward from the axis. Effect on g: g ′ = g − ω 2 R cos ⁡ 2 λ g ′ = g − ω 2 R cos 2 λ 2. Coriolis Force (affects moving objects) Cause: Motion relative to rotating Earth. Formula:   F ⃗ c o r = − 2 m ( ω ⃗ × v ⃗ ) F cor ​ = − 2 m ( ω × v ) Direction: Perpendicular to motion; does no work (changes direction only). Deflection: Right in N. Hemisphere, Left in S. Hemisphere. Examples: Cyclones, ocean currents, trade winds, Foucault pendulum, projectile drift.