PhysicsKund Physics class 9 to 12 NCERT, JEE - NEET

Interference of Light Interference of light is the phenomenon in which two or more coherent light waves superpose and redistribute light intensity in space, producing regions of maximum and minimum intensity. Principle of Superposition The phenomenon of interference is based on the Principle of Superposition, which states: When two or more light waves overlap at a point, the resultant displacement at that point is equal to the vector sum of the displacements produced by the individual waves. Conditions for Sustained Interference The sources must be coherent. The waves must have the same frequency or wavelength. The phase difference between the waves should remain constant. The amplitudes should be nearly equal for clear interference patterns. Types of Interference 1. Constructive Interference Constructive interference occurs when two waves meet in the same phase. The resultant amplitude becomes maximum, producing maximum intensity. Condition: $\Delta = n...

  Kundt’s tube is a classic experimental physics apparatus invented in 1866 by German physicist August Kundt. It provides a striking, real-world method to visualise invisible sound waves and accurately measure the speed of sound through various gases and solid materials. By trapping sound waves inside a controlled chamber, the device forces a fine powder to settle into geometric patterns that map out the physical structure of the wave itself. 1. Video Demonstration & Explanation Watch how the standing waves manipulate dust particles inside the tube in this laboratory experiment demonstration. 2. Underlying Physics: Standing Waves and Resonance The operation of Kundt's tube relies entirely on the phenomenon of acoustic resonance and the creation of standing waves. When a sound source generates longitudinal waves at one end of a closed tube, the waves travel down the length of the cylinder and reflect off the opposite, closed boundary. The forward-moving waves and the...

Rutherford's Atomic Model According to Rutherford's nuclear model, an atom consists of a tiny, dense, positively charged nucleus at its centre, around which electrons revolve in circular orbits. Salient Features An atom has a small, dense, positively charged nucleus. Almost the entire mass of the atom is concentrated in the nucleus. Electrons revolve around the nucleus in circular orbits. The electrostatic force of attraction between the nucleus and electrons provides the necessary centripetal force. Most of the space inside an atom is empty. Electron Orbits Let, e = charge on electron Ze = charge on nucleus m = mass of electron v = velocity of electron r = radius of orbit ε 0 = permittivity of free space 1. Electrostatic Force of Attraction The electrostatic force between the nucleus and electron is given by: F e = Ze² / (4πε 0 r²) 2. Centripetal Force The centripetal force required for circular motion is: F c ...

Definition of Nuclear Fission  Nuclear fission is the process in which a heavy nucleus splits into two or more lighter nuclei when bombarded by a neutron. A large amount of energy and neutrons are released during this process. Example of Nuclear Fission When a slow neutron strikes a Uranium-235 nucleus, it first forms an unstable Uranium-236 nucleus. This unstable nucleus then splits into two lighter nuclei. Nuclear Reaction $${}^{1}_{0}n + {}^{235}_{92}U \rightarrow {}^{236}_{92}U$$ $${}^{236}_{92}U \rightarrow {}^{144}_{56}Ba + {}^{89}_{36}Kr + 3\,{}^{1}_{0}n + \text{Energy}$$ Important Points About Nuclear Fission Uranium-235 is a fissile material. Nuclear fission is a neutron-induced reaction. Two or more lighter nuclei are formed. 2 to 4 neutrons are released. The fission fragments are radioactive. They emit beta particles and eventually become stable. Energy Released in Nuclear Fission The energy released during fission is called the Q-valu...

Notes : CBSE Class 12 Physics Chapter 13 Nuclei - Physics Kund Composition of the Nucleus of an Atom Atomic Mass Unit Proton: Definition, Discovery and Properties Neutron: Definition, Discovery and Properties Define Isotopes, Isobars and Isotones with Example Size of the Nucleus: Derivation of Radius and Nuclear Density Einstein Mass-Energy Relation Mass Defect and Nuclear Binding Energy Binding Energy per Nucleon and its Variation with Mass Number Nuclear Force Radioactivity Nuclear Fission Nuclear Fusion

Thermodynamic State Variables and Equation of State Every equilibrium state of a thermodynamic system is completely described by a set of macroscopic quantities known as Thermodynamic State Variables or State Functions . What are Thermodynamic State Variables? State variables are measurable physical quantities that define the state of a thermodynamic system when it is in thermodynamic equilibrium. For a gas, the common state variables are: Pressure ($P$) Volume ($V$) Temperature ($T$) Mass ($M$) Number of moles ($\mu$) These variables completely describe the equilibrium state of the system. Condition for State Variables State variables can only be assigned meaningful values when the system is in a state of thermodynamic equilibrium. In equilibrium: Temperature is uniform throughout the system. Pressure is uniform throughout the system. No net macroscopic changes occur with time. Non-Equilibrium States When a system changes rapidly, pressure and temper...