Physics Education

Coolidge X-ray tube Construction It consist of vacuum glass chamber in which filament is connected to negative terminal of the battery (in several KV) & Copper block is connected to the positive terminal of the battery. An arrangement is made to heat the filament through heating coil which is connected to a small battery (5-10 V). The front of the copper block is coated with tungsten. A cooling arrangement is made at the back of copper block. click here to know more about x-ray Working When voltage is applied to the heating coil; heat is generated. This heat; heated up the filament & because of thermionic emission; filament generate electrons which have very low kinetic energy. When these electrons comes out from filament, due to very high electric field between anode (Target) & cathode (filament); these electrons get accelerated & moves with very high kinetic energy towards the target. Electrons with high Kinetic energ...

Introduction/Properties of X-ray Discovered by W.C Roetgen in 1895 & received first Nobel Prize for physics in 1902.When high energetic electrons are incident on a metal target (Melting point & atomic weight) then x-rays are emitted. Electromagnetic waves Invisible No deflection in electric & magnetic field therefore it is made up of  Photon. Hence it has no  mass and charge. click here to know more about photon Penetrating power is very high. X-rays with longer wavelength (or lesser frequency it means lesser energy) are called soft x-rays. X-rays with shorter wavelength are called hard x-rays. Types of X-rays Characteristics or line X-rays Continuous X-rays Characteristics X-rays When high energetic electrons are strike on a metal target; they knock out electrons from innermost shell like K, L, M etc. & the vacancies created are filled by higher orbital (shells). Electrons from h...

Photo electric cell It is an electronic device which converts light energy into electrical energy. It works on the principle of photo electric effect. Construction It consists of a glass tube, two electrodes - cathode & anode. Cathode is concave in shape & coated with photosensitive material. Cathode is connected to negative terminal & Anode is connected to the positive terminal of the battery. click here to know about photo electric effect Working When a light ray of suitable frequency is incident on the concave surface of the cathode, it emits electrons. These photo-electrons are attracted by the anode & flow through external circuit which produces photo electric current. This current is measured using micro ammeter (mA) connected in series with anode. When Intensity of light increases, photo electrons increases & hence photo electric current increases. like facebook page for latest update Applicati...

Properties of photon  – They have zero mass. They only exist as moving particles They have no electric charge. They carry energy which is proportional to the frequency of light. They travel with the speed of light. Intensity of light depends upon number of photons per unit area. All these photons have same frequency & wavelength. Each photon have same energy. click here to know Einstein photo electric equation like facebook page for latest update Energy of Photons                                                             E ∝  𝜈                                                             E  =h𝜈  Joules ...

Photo electric effect - The emission of electrons from a metal plate when illuminated by light of suitable frequency or wavelength is called photoelectric effect. The emitted electrons are called photo-electrons. click here to know about photo electric cell Explanation   It consist of two photosensitive surfaces A & B in a transparent tube. Plate A is connected to negative terminal of the battery while Plate B is connected to positive terminal through galvanometer. In the absence of light there is no flow of current. Hence there is no deflection in the galvanometer. When a light of suitable frequency or wavelength falls on plate A, electrons are ejected out & attracted by the Plate B. Current starts flowing in the circuit indicated by the galvanometer. like our facebook page for latest update Characteristics of Photoelectric effect Photoelectric effect is not possible below the threshold frequency. The nu...

Population Inversion Normally the population density of electron is more in the lower energy level than the higher energy level.  i.e., Na > Nb The process of achieving greater population density of electrons in the higher energy level as compared to lower energy level is called population inversion. like our facebook page for latest update Pumping method   The process by which atoms are raised from lower energy level to the upper energy level so that necessary population inversion is obtained is called pumping. There are various methods of laser pumping:- i)               Optical Pumping - To raise the electron from lower energy level to higher energy level, if we use light energy (Photon) then this pumping is known as optical pumping. ii)          Direct electron excitation - In a discharge tube when a pote...

Holography The word holography originates from the Greek words "holos" (complete) & "graphos" (writing). Thus it is the technique to record the complete picture of an object. The technique was proposed by Dennis Gabor in 1948 for which he received Nobel prize in 1971. Holography is also called as lensless photography . In normal photography only the intensity of light (reflected from object) is recorded but in holography the intensity of light as well as phase of light is recorded; the record is called hologram. By holography we get a 3-dimensional image. like our facebook page for latest update Holography consists of two processes – (i) Recording of hologram.                  (ii) Reconstructing of image. Recording of hologram   It is based on the phenomenon of Interference. A laser beam from the laser source is incident on beam splitter. As the name suggests, the function of t...

Introduction   Modern physics is a branch of physics which deals with the discoveries in twentieth century. One of the best discoveries in twentieth century is "Photoelectric effect" explained by Albert Einstein. He received Nobel Prize for photoelectric effect in 1921. click here to know about photo electric effect Black-body Radiation -  When a white ray falls on a normal body; the three cases occurs- Absorption - some part of the white light is absorbed by the normal body. Reflection - only one color is reflected by the body because the body already have that color. Reflected color enters into our eyes and we are able to perceive the actual color of the body. Transmission - some part of the white light goes through the normal body.                But when a white ray falls on a body which absorbs all the white ray is known as black body . E.g. Charcoal, layer made by carbon etc. like facebook page for latest up...

Introduction to LASER: - Laser is the acronym for light amplification stimulated emission of radiation. The first successful laser was Ruby laser, invented in 1960 by American physicist Theodore Maiman. It is use to provide intense, monochromatic & completely coherent light. It works on the principle of stimulated emission.   Properties of a laser:- 1) Monochromatic: - Single color & single wavelength. 2) Divergence & Directivity: - Beam is well collimated (Parallel) & travels long distance with very less spread. 3) Coherence: - All the individual waves of light moves - precisely (Exactly) together through time & space. 4) Intensity: - The intensity of the laser beam is very high. E.g. If a person is allowed to observe an ordinary light by 100 W bulb, he receive only 1/1000th of it at a distance of 1 foot. But he observes a laser beam at the same distance, the laser beam penetrate through eyes & it wi...