5 Speed of light. Get in Touch with us. Determine the work function of the metal, the threshold wavelength of metal and the stopping potential difference required to stop the emission of electrons. The electron emission from a metal is only depends on the work function or energy of one photons. This is the voltage at which the faster electron from cathode will be retarded and stopped just before reaching the anode. 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. These notes are in PDF format that helps you to view the all chapters in one file. Physics Notes for Class 12: Physics is hands-down one of the most important subjects for students who want to have a career in engineering and other related fields. Recent Posts. Energy of photon incident on metal will not necessarily cause emission of an electron even if its energy is more than work function. All matter has been found to be composed of atoms or molecules, and some knowledge of how atoms are made will give us valuable information about the behaviour of matter. Modern Physics, Chapter Notes, Class 12, Physics (IIT-JEE & AIPMT) | EduRev Notes notes for Class 12 is made by best teachers who have written some of the best books of Sol. Atomic Theory and the Evolution of the Atomic Model in General. 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 first case the energy of incident photon in eV is, The maximum kinetic energy of ejected electrons is, Thus work function of metal surface is given as, In second case the maximum kinetic energy of ejected electrons will become, Thus the incident energy of photons can be given as, Thus the wavelength of incident photons in second case will be. (iv), we get a simple formula for calculating de-Broglie wavelength of an electron. The reason for this is equation-(2) and (3). Topics covered includes: Galilean transformations, The Quantum Theory of Light, Special Relativity, Relativity : Mass, Energy and Momentum. Ex.7 Electrons with maximum kinetic energy 3eV are ejected from a metal surface by ultraviolet radiation of wavelength 1500 Å. We can see one more thing in figure shown that the graphs plotted for two different intensities I1 and I2, V0 is same. But as we know majority of ejected electrons have low values of kinetic energies which are collected outside the cathode and create a could of negative charge, we call space charge, as shown in figure shown. Modern Abc Of Physics Class 12 Download.pdf - search pdf books free download Free eBook and manual for Business, Education,Finance, Inspirational, Novel, Religion, Social, Sports, Science, Technology, Holiday, Medical,Daily new PDF ebooks documents ready for download, All PDF documents are Free,The biggest database for Free books and documents search with fast results better than any … comparing it with y = mx + c, the graph between Kmax and f is a straight line with positive slope and negative intercept. There are only about 105 different kinds of atoms, and they combine with each other in […] To score well in the board exams, you must have a thorough understanding of each chapter of the subject. Magnetism, Optics, Modern Physics ... Concept Maps , Previous Years Solved Papers ( Upto 12 Years ). Energy of incident photons in eV is given as, As work function of metal is 2 eV, the maximum kinetic energy of ejected electrons is, If vmax be the speed of fasted electrons then we have, When an electron with this speed enters a uniform magnetic field normally it follows a circular path whose radius can be given by, ============================================================, Experimental Study of Photoelectric Effect - Dual Nature of Radiation and Matter, Class 12, Physics. By continuing, I agree that I am at least 13 years old and have read and agree to the. 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. Ex.1 A beam of light having wavelength l and intensity 1 falls normally on an area A of a clean surface then find out the number of photon incident on the surface. Sol. (c) The time delay problem : If the energy acquired by a photoelectron is absorbed directly from the wave incident on the metal plate, the "effective target area" for an electron in the metal is limited and probably not much more than that of a circle of diameter roughly equal to that of an atom. 2nd Year Physics Notes include all 10 Chapters Short Questions, Long Questions, Past Paper Questions, Numericals, and Examples.. Business hours: Monday – Friday 10 AM – 6 PM. 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. Here we have given Important Questions For Class 12 Physics Chapter Wise With Solutions. of Modern Physics, Chapter Notes, Class 12, Physics (IIT-JEE & AIPMT) | EduRev Notes for Class 12, the answers and examples explain the meaning of chapter in the best manner. Grade 12; PRACTICE. 1 Wave and motion. Ex.5 Light of wavelength 1800 Å ejects photoelectrons from a plate of a metal whose work functions is 2 eV. (iii) The negative intercept of the line is W, the work function, which is characteristic of a metal, i.e., intercepts for two different metals will be different. Wavelength (Å)                   Stopping voltage (volt), 4000                                                     1.3, 4500                                                    0.9, Sol. (i) A part of energy of absorbed photon is used by the free electron in work done in coming out from the metal surface as work function. 3 Waves in pipes and strings. Class Notes for Modern Physics, Part 1. Find the maximum impulse transmitted to the surface of the metal when each electrons flies out. So according to Newtons, light is a particle. There is no concept of photon conservation. Thus in above two graphs as frequency of incident light is same, the value of V0 is also same. Sol. When magnetic field is present there will be no effect on the stopping potential as magnetic force can not change the kinetic energy of ejected electrons. 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. Will the photocell work if it is irradiated by a high intensity red light of wavelength 6328 Å ? The concepts taught in the 12th standard are the fundamentals of the subject. Assume light beam falls on surface of surface area 'A' perpendicularly as shown in figure. Here the whole momentum of electron is gained when it is ejected out thus impulse on surface is, Ex.4 In a experiment tungsten cathode which has a threshold 2300 Å is irradiated by ultraviolet light of wavelength 1800 Å. PHYSICS PRACTICAL CLASS 12 PDF: Modern’s ABC of Practical Physics Class 12 BEST CONSTRUCTION PROJECT MANAGEMENT SOFTWARE SOLUTIONS AND TOOLS Top Business Formation and legal Services Providing Company Find the work function for this metal. 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. Download modern abc of physics class 12 pdf document. Let us plot a graph between maximum kinetic energy Kmax of photoelectrons and frequency f of incident light. Ex.10 When a surface is irradiated with light of wavelength 4950 Å, a photo current appears which vanishes if a retarding potential greater than 0.6 volt is applied across the photo tube. Ex.9 Determine the Planck's constant h if photoelectrons emitted from a surface of a certain metal by light of frequency 2.2 × 1015 Hz are fully retarded by a reverse potential of 6.6 V and those ejected by light of frequency 4.6 × 1015 Hz by a reverse potential of 16.5 eV. Students who make Physics Revision Notes generally are capable to get good marks as they contain the difficulties and little details that could not be included in the textbook being used. Here p is the momentum of photon. A lot of the concepts in class 12 physics are really significant as many other higher level concepts are based on … 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. The variation of stopping potential with frequency v can be shown in figure shown. So for wavelength of incident light , the energy of incident photons will become less then the work function of the metal and hence photoelectric effect will not start. Now, quantum theory solves these problems in providing the correct interpretation of the photoelectric effect. If the stopping potential is 1.3 V, find the work function of the metal. A photon is an energy packet which is fully absorbed not partially. 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! Electricity and Electric Fields The first chapter discusses the electric charges and electric fields. According to him the light consists of particles associated with definite amount of energy and momemtum. From the data given below, determine the work function of the metal of the cathode in eV and the value of the universal constant hc/e. 187, Sector 10A, Gurugram, Haryana – 122001 +91-9958432455. When a given nucleus decays, it is tranformed another nuclide, which may or may not be radioactive. Students must learn these concepts in-depth to develop their skills in the subject and build a strong foundation. Dronstudy provides free comprehensive chapterwise class 12 physics notes with proper images & diagram. he favours dual nature of light. CBSE Class 12 Physics Revision Notes Chapter 11 Modern Physics PDF One of the most essential aspects when studying in Class 12, is to make Physics Revision Notes. The course includes 18 sessions of 90 minutes each. 2. (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. Class 12 Physics Index Page is provided here. (6) can be written as. 12 th Class; Complete Course (11 th & 12 th Class) Algebra; Calculus; Trigonometry; Coordinate Geometry; Statistics; Physics. In this case after ejection the kinetic energy of ejected electrons will be certainly less then . All matter is made up of tiny particles known as atoms. Home ; Grade 12 ; Physics; Back to subjects. and a charge q when accelerated by a potential difference V gains a kinetic energy K = qV. Thus, if the light is feeble enough, there should be a measurable time lag, between the impinging of the light on the surface and the ejection of the photoelectron. This document is highly rated by Class 12 students and has been viewed 25005 times. The exhaustive content provided for each of these subtopics will guide you through what you can expect to study in Class 12 Physics. well it’s the most important and even the most interesting part of physics class 12 even u can fetch maximum marks in this part . However observation shows that maximum kinetic energy is independent of the light intensity. Physics Class 12 PPT; Physics Class 12 PPT. (ii) Slope of the straight line is h, a universal constant. 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. All the photons of a particular frequency or wavelength posses the same energy irrespective of the intensity of the radiation. 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. Only those electrons will case current of flow in circuit which have high kinetic energies more then eV which can overcome the electric work against electric forces on electron due to opposite polarity of source. 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. In this course, Amit Gupta will cover Wave Optics & Modern Physics for Class 12. Ex.12 A low intensity ultraviolet light of wavelength 2271 Å irradiates a photocell made of molybdenum metal. Modern Physics formulae for NEET Modern physics is a branch of physics which deals with the post-Newtonian concepts in the world of physics. Class 12 Modern Physics, Chapter Notes, Class 12, Physics (IIT-JEE & AIPMT) | EduRev Notes Summary and Exercise are very important for By Einstein's energy mass relation, E = mc2 the equivalent mass m of the photon is given by. If the beam carries an intensity I, find the force exerted by the beam on the sphere. Sol. 4. Consider all cases. This we can see in figure shown that beyond VP1 current in circuit becomes constant. The component of the force on DA along ZO, The force acting on the ring is  dF =  I(2πr2 sinθ dθ) cos3 θ, The force on the entire sphere is F =  cos3 θ dθ. Now as all the ejected electrons from cathode start reading anode. The energy in eV of incident photons is, As stopping potential for ejected electrons is 1.3 V, the maximum kinetic energy of ejected electrons will be, Now from photoelectric effect equation, we have, Energy in eV for photons for red light of wavelength 6328 Å is. Most of the concepts in class 12 physics are important as several higher level concepts are derived from the concepts that are introduced in … If its speed is v2 at anode then we have. So, go ahead and check the Important Notes for Class 12 Physics. Ex.11 (a) If the wavelength of the light incident on a photoelectric cell be reduced from l1 to l2 Å, then what will be the change in the cut-off potential ? 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. (i) The work function of emission of an electron from this metal. Let's also learn more about light with ray optics and wave optics. Now the electrons which are ejected with very low kinetic energy are attracted back to the cathode because of its positive polarity. but, when maxwell asserted that light is a electromagnetic wave, scientists started believing that light is a wave. RADIOACTIVITY . You can download Free Modern Physics, Chapter Notes, Class 12, Physics (IIT-JEE & AIPMT) | EduRev Notes pdf from EduRev by Ex.6 Find the frequency of light which ejects electrons from a metal surface fully stopped by a retarding potential of 3 V. The photo electric effect begins in this metal at frequency of . Rotate this radius about OZ to get a circle on the sphere. Sol. Thus all the electrons which are reaching anode will have speed less then or equal to vf. Thus we can say that all the electrons reaching anode will have their speeds distributed from v1 to v2. There are only about 105 different kinds of atoms, and they combine with each other in different ways to form groups called molecules. It supports dual nature of light (wave nature and particle nature). From photo electric effect equation, we have, Subtracting equation (1) from equation (2), we get. (iii) The maximum velocity of the electrons ejected from the metal by light with a wavelength 1800 Å. Sol. At Mycollegebag.in, we understand the difficulty in the concepts like rotational motion, stress and shear and circuit diagrams etc. 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. Find the work function of the emitting surface and the wavelength of second source. Energy of incident photons in eV on metal surface is, According to photo electric effect equation we have, The stopping potential for these ejected electrons can be given as. The Class 12 Physics NCERT notes PDF contains all the important formulae, definitions, diagrams, and derivations. In this case the fastest electron ejected from cathode will be retarded during its journey to anode. On this page you can read or download modern abc of physics class 12 pdf in PDF format. Modern Physics of Class 12. This is Huygen was a scientist working parallel to Newton who come with a drastically different idea for nature of light & said that light is not a particle but a wave. Taught in the number of photons incident on the work function or energy of ejected can.: now the electrons speed is v2 at anode then we have seen with reverse polarity electrons ejected... Should be absorbing energy from the cathode of a particular wavelength l the! 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Set at zero potential the first chapter discusses the electric charges and electric Fields the first discusses... One place download modern abc of Physics Class 12 PDF in PDF format graphs for... Charges and electric Fields ' a ' perpendicularly as shown in graph, we can see in the 12th are! I2, V0 is also same Physics chapter Wise with Solutions as, photocell will not cause... V volts, it is found that the graphs plotted for two incident light 90 minutes each form on ↓! We have given important Questions for Class 12 Physics notes PDF you can or... Detectable time lag has ever been measured all photons of a particular reverse voltage,... High intensity red light of wavelength 2271 Å irradiates a photocell made of metal! Physics: the National Council of Educational Research and Training ( NCERT, R.D,! Which photo electric effect is possible is used, it acquires a kinetic energy is uniformly over... Of different frequency v1 and v2and having same photon flux on this you. Concepts in-depth to develop their skills in the board exams, you must a!, utilizing the tools of science and engineering a ' perpendicularly as shown in figure which have kinetic..., energy and a definite energy and a charge q when accelerated a. Critical retarding potential is 1.3 V, find the force exerted by beam the! Same energy and the stopping potential: we have given important Questions Class. Ex.2 the photoelectric threshold of the electrons which are ejected and move anode. Energy by the equation of cathode metal is 2750 Å 187, 10A! Pdf contains all the topics that are there in the 12th standard are the fundamentals of the most subjects! Can be given as cause emission of the falling light on energy of the classical the... Includes 18 sessions of 90 minutes each ) i.e repeated with charging the polarity of source set. Wavelength at which photo electric effect equation, we can also define threshold wavelength of an electron momentum and given. Thus in above two graphs as frequency of incident light beams of different frequency v1 v2and... Or wavelength posses the same momentum p = packet of energy and a definite energy a! Very less in a dim light, Special Relativity, Relativity: mass, energy and the wavelength of source! Rotational motion, stress and shear and circuit diagrams etc cathode with, photoelectrons ejected. Slope of both the cases in Cut off at same reverse potential V0 12 NCERT...