1.6 Three Major Features of the Phtoelectric effect cannot be explained in terms of the classical of the wave theory of light. In general, the term is used to refer to any branch of physics either developed in the early 20th century and onward, or branches greatly influenced by early 20th century physics. In this course, Amit Gupta will cover Wave Optics & Modern Physics for Class 12. This reverse potential difference V0 at which the fastest photoelectron is stopped and current in he circuit becomes zero is called cut off potential or stopping potential. Download CBSE Class 12 Physics Modern Physics Exam Notes pdf, Physics revision notes, mind maps, formulas, examination notes, sure shot questions, CBSE Class 12 Physics Modern Physics Exam Notes. This document is highly rated by Class 12 students and has been viewed 25005 times. Electrostatics; Dual Nature of Radiation and Matter and Atoms and Nuclei; Electronic Devices and Communication Systems; Current Electricity; Heating and Chemical Effects of Current; Magnetic Effect of Current; Magnetism; Electromagnetic Induction; Alternating Currents; Ray Optics; Wave Optics; Electrons, Photons and X … This is briefly described over here. In this session, Anu Gupta Sir will be discussing Modern Physics – Photoelectric Effect, NEET important questions of Modern Physics and tips & tricks to solve questions and will help you revise the topic according to NEET 2021. If a light beam of frequency n (each photon energy = hn) is incident on a metal surface having work function f then for , we have. This is The NCERT Physics Books are based on the latest exam pattern and CBSE syllabus. Ex.13 Calculate force exerted by light beam if light is incident on surface at an angle q as shown in figure. Now as all the ejected electrons from cathode start reading anode. By Einstein's energy mass relation, E = mc2 the equivalent mass m of the photon is given by. Sol. (a) Let the work function of the surface be f. If v be the frequency of the light falling on the surface, then according to Einstein's photoelectric equation, the maximum kinetic energy KEmax of emitted electron is given by. Physics is one of the most interesting subjects which is filled with numerous engaging concepts. If we assume there are some electrons which do not loose any energy in the process of ejection, will come out from the metal surface with the maximum kinetic energy given as. Modern Physics of Class 12. Change q to q +dq and rotate the radius about OZ to get another circle on the sphere. your class 12 physics is divided in 2 volumes .modern physics comes in the 2nd volume of NCERT textbook. Those electrons which have high kinetic energies will rush toward, anode and may constitute the current in circuit. (b) Light is incident on the cathode of a photocell and the stopping voltages are measured from light of two difference wavelengths. this is your one stop solution. 1.3 Maxwell's electromagnetic wave theory : During the time of Hygen, his views regarding nature of light were not accepted as newton was a popular scientist of his time. It supports dual nature of light (wave nature and particle nature). Find the work function of the emitting surface and the wavelength of second source. Being a vital part of the physics syllabus for Class 12, modern physics consists of a variety of foundational topics and some of these have been mentioned below: Black-Body Radiation. Kinetic Energies of Electrons Reaching Anode, We know that when electrons are ejected from cathode then kinetic energies may vary from 0 to . When light travels from one medium to another medium then, frequency = const (because it is the property of source). As the maximum kinetic energy just after emission at cathode is , if potential difference across the discharge tube is V then the seed vf with which electrons will reach anode can be given as. If you want Modern Physics, Chapter Notes, Class 12, Physics (IIT-JEE & AIPMT) | EduRev Notes This will help a student save time. What retarding potential is necessary to stop the emission of the electrons ? (ii) Slope of the straight line is h, a universal constant. 11 th Class; 12 th Class; Complete Course (11 th & 12 th Class) Kinematics & Rotational Motion; Modern Physics; Optics; Mechanics; Heat and Thermodynamics; Waves and Oscillations; Electricity and Magnetism; Chemistry. Momentum is related to the kinetic energy by the equation. (ii) Maximum kinetic energy of these electrons. The minimum amount of energy of photon required to eject an electron out of a metal surface is called work function It is denoted by φ. The chapters and subtopics listed below are according to the latest syllabus of Central Board of Secondary Education. There are only about 105 different kinds of atoms, and they combine with each other in different ways to form groups called molecules. NCERT Books Class 12 Physics: The National Council of Educational Research and Training (NCERT) publishes Physics textbooks for Class 12. The electron emission from a metal is only depends on the work function or energy of one photons. Consider all cases. Radioactive decay is a random process: Each decay is an independent event, and one cannot tell when a particular nucleus will decay. You can download Free Modern Physics, Chapter Notes, Class 12, Physics (IIT-JEE & AIPMT) | EduRev Notes pdf from EduRev by The increase in the intensity of the radiation imply an increase in the number of photon's crossing a given area per second. EduRev is like a wikipedia Debroglie relates particle property (momentum) with wave property (wavelength) i.e. This current is1 is called saturation current. textbook detailed solutions (NCERT, R.D Sharma, HC Verma & etc. but, when maxwell asserted that light is a electromagnetic wave, scientists started believing that light is a wave. Topics covered includes: Galilean transformations, The Quantum Theory of Light, Special Relativity, Relativity : Mass, Energy and Momentum. According to him the light consists of particles associated with definite amount of energy and momemtum. Thus we can say that all the electrons reaching anode will have their speeds distributed from v1 to v2. Now the electrons which are ejected with very low kinetic energy are attracted back to the cathode because of its positive polarity. Sol. Physics Notes for Class 12 Download. Physics. Here p is the momentum of photon. the electron which is ejected from cathode with zero kinetic energy will be the slowest one reaching the anode if its speed is v1 at anode then we have, Similarly the electron ejected from cathode with maximum kinetic energy will be the fastest one when it will reach anode. just for education and the Modern Physics, Chapter Notes, Class 12, Physics (IIT-JEE & AIPMT) | EduRev Notes images and diagram are even better than Byjus! Assume light beam falls on surface of surface area 'A' perpendicularly as shown in figure. 4. When light is incident on a metal surface it was observed that electrons are ejected from a metal surface some times even when incredicely dim light such as that from starts and distance galaxies incident on it and some time electrons not comes out from the metal surface even high energetic or high intensity light falling on the metal surface. Important Questions for Class 12 Physics Chapter Wise With Solutions. Photons no matters in number of photons are very less in a dim light, photo electric effect can be seen. These here V01 and V02 can be given as, In general for a given metal with work function, if Vo is the stopping potential for an incident light of frequency v then we have, Equation (7) shows that stopping potential V0 is linearly proportional to the frequency v of incident light. This shows that the electron emission from a metal surface is not depends on the intensity of incident light but it is basically depends on the energy of the incident. Beyond VP2, we can see that all the electrons ejected from cathode are reaching the anode are current become saturated at is2 because of more electrons. Now if the frequency of incident light is kept constant and its intensity is further increased, then the number of incident photons will increase which increases the number of ejected photo electrons so current in circuit increases and now in this case at higher intensity of incident light, current will not get saturated at potential difference VP1 as now due to more electron emission, space charge will be more and it will not vanish at VP1. where p is the momentum of the particle. 2 Mechanical Wave. initial momentum of photon (in downward direction at an angle q with vertical) is h/λ, change in momentum (in upward direction at an angle q with vertical) =  [ ], energy incident per unit time = I A cos θ, total change in momentum per unit time (in upward direction at an angle q with vertical), Force (F) = total change in momentum per unit time, Therefore, change in momentum of one photon, Therefore, total change in momentum per unit time, Therefore, force on the plate  (downward), change in momentum of photon when it is reflected = (downward), change in momentum of photon when it is absorbed =  (in the opposite direction of incident beam), energy incident per unit time = I A cos θ), force on plate due to absorbed photons Fa = na. The photon posses momentum and is given by, A photon is a packet of energy. During this interval the electron should be absorbing energy from the beam until it had accumulated enough to escape. In graph II as frequency of incident light is more, the maximum kinetic energy of photoelectrons will also be high and to stop it high value of stopping potential is needed. Consider a small part DA of this ring at P. Energy of light falling on this part in time Dt is, The momentum of this light falling on ΔA is ΔU/c along QP. The Physics Notes PDF for Class 12 provided by Vidyakul cover all important topics included in NCERT Syllabus. There are only about 105 different kinds of atoms, and they combine with each other in […] The modern era is the result of the progress in Physics, and its laws are interpreted every day … On this page you can read or download modern abc of physics class 12 pdf in PDF format. out Class 12 lecture & lessons summary in the same course for Class 12 Syllabus. A lot of the concepts in class 12 physics are really significant as many other higher level concepts are based on … At this time there was a great confusion about the nature of light which was solved by de-broglie from where origin of theory of matter wave come into picture. If a uniform magnetic field of tesla is applied parallel to plate, what would be the radius of the path followed by electrons ejected normally from the plate with maximum energy. Examination notes which you can use for preparing and revising for exams plate of a metal photoelectric! 1800 Å ejects photoelectrons from metal with work function of the wave of. Will be nr ΔPr wavelength for an electron positive polarity from equation ( 2 ), we.... At Mycollegebag.in, we get their speeds distributed from v1 to v2 1.10 potential. Per second the given download button each electrons flies out is highly by! In the subject and build a strong foundation surface by ultraviolet radiation of wavelength 1500 Å course! 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