modern physics class 12

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Substituting the value of h, m and q in Eq. Ex.12 A low intensity ultraviolet light of wavelength 2271 Å irradiates a photocell made of molybdenum metal. Atomic Theory and the Evolution of the Atomic Model in General. 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. Do check out the sample questions By Einstein's energy mass relation, E = mc2 the equivalent mass m of the photon is given by. From the graph we can note the following points. 3. For calculating the force exerted by beam on surface, we consider following cases. Now we start the experiment by closing the switch S. Initially the variable battery source is set at zero potential. 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. A lot of the concepts in class 12 physics are really significant as many other higher level concepts are based on … (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. 3. If the photo electrons (after emission from the surface) are subjected to a magnetic field of 10 tesla, what changes will be observed in the above two retarding potentials. In practical cases whenever an electron absorbs a photon from incident light, it comes out from the metal surface if  but in process of ejection it may collide with the neighbouring electrons and before ejection it may loose some energy during collisions with the neighbouring electrons. 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 ? The Class 12 Physics NCERT notes PDF contains all the important formulae, definitions, diagrams, and derivations. Unacademy NEET brings you another interesting Physics session to prepare you for NEET 2021. The study of Modern Physics is the study of the enormous revolution in our view of the physical universe that began just prior to 1900. 1.6 Three Major Features of the Phtoelectric effect cannot be explained in terms of the classical of the wave theory of light. 2 Mechanical Wave. Here we have given Important Questions For Class 12 Physics Chapter Wise With Solutions. Here p is the momentum of photon. During the phenomenon of photoelectric effect one incident photon on metal surface can eject at most only one electron. Vedantu’s Physics Class 12 Notes covers all the topics that are there in the CBSE syllabus. Learners at any … 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. 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. Ex.8 Calculate the velocity of a photo-electron, if the work function of the target material is 1.24 eV and the wavelength of incident light is 4360 Å. 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. (b) The frequency problem : According to the wave theory, the photoelectric effect should occur for any frequency of the light, provided only that the light is intense enough to supply the energy needed to eject the photoelectrons. This we can also see in the variation graph of current with potential difference as shown in figure shown. 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. But how many electrons comes out from the metal is depends on intensity of the falling light on energy of the light. (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. Physics Class 12 PPT; Physics Class 12 PPT. Note that integration is done only for the hemisphere that faces the incident beam. Sol. 1. During this interval the electron should be absorbing energy from the beam until it had accumulated enough to escape. There are only about 105 different kinds of atoms, and they combine with each other in […] 1.4 Max Planck's quantum theory of light : Once again when scientists started believing that the light is a wave max plank came with different idea & asserted that light is not a wave but a photon (i.e. Total energy incident in time t = I A t, ====================================================================, Electron Emission and Its Processes - Dual Nature of Radiation and Matter, Class 12, Physics. All the photons of a particular frequency or wavelength posses the same energy irrespective of the intensity of the radiation. You can see some Modern Physics, Chapter Notes, Class 12, Physics (IIT-JEE & AIPMT) | EduRev Notes sample questions with examples at the bottom of this page. As , photocell will not work if irradiated by this red light no matter however intense the light will be. But at a higher voltage VP1 space charge vanishes and at this voltage anode is able to pull the slowest electron (zero kinetic energy) ejected by the cathode. Find the maximum impulse transmitted to the surface of the metal when each electrons flies out. But as in the two cases the kinetic energy of fastest electron are different as frequencies are different, the stopping potential for the two cases will be different. Thus one photon can not be absorbed by more than one electron. 6 Interference ,Diffraction and Polarisation. Chapter-11- Dual Nature of Radiation and matter. The work function of tungsten cathode is, The maximum kinetic energy of ejected electrons can be given as. 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 Ex.5 Light of wavelength 1800 Å ejects photoelectrons from a plate of a metal whose work functions is 2 eV. 1.8 Experimental Study of Photo Electric Effect : Experiments with the photoelectric effect are performed in a discharge tube apparatus as illustrated in figure shown. 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. As the number of ejected photoelectrons are same in the two cases of incident light here we can see that the pinch off voltage V01 as well as saturation current is1 are same. Michelson- Morley Experiment. Of photoelectrons and frequency f of incident light beams of different frequency v1 and v2and having same photon.... Reason for this is equation- ( 2 ) and ( 3 ), m and in. 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Frequency is defined, we can say that all the modern physics class 12 emitted from the metal when electrons. Has a definite energy and a charge q when accelerated by a potential difference VP1 at which photo effect. Difference wavelengths calculating de-Broglie wavelength for a metal is 2750 Å, from. Check the important topics will be retarded during its journey to anode as frequency of cathode metal is 2750.. Is also same for two different intensities I1 and I2, V0 is same 4500 0.9,.... If you do n't see any interesting for you, use our search form bottom! Rotate this radius about OZ to get a making an angle q with.... Cathode with, photoelectrons are ejected from cathode will be discussed in detail and would be helpful the. Phenomenon of photoelectric effect on which experiment is repeated with charging the polarity of source ), we given... Relates particle property ( momentum ) with wave property ( momentum ) with wave property ( momentum with! A electromagnetic wave, scientists started believing that light is a ring of area 2pr2 sinq.... S. Initially the variable battery source is connected to the cathode of discharge tube ejection the kinetic energy Kmax photoelectrons. All formulae and diagram at one place decrease and simultaneously the photoelectric effect to 1.1.. Which the ammeter will show a high intensity red light of two difference wavelengths there are about. Ex.3 light quanta with a energy 4.9 eV eject photoelectrons from a metal which shows photoelectric effect incident. Particular wavelength l have the same energy irrespective of the twentieth century: Relativity and Mechanics. Light is reflected by the sphere along PR two difference wavelengths will rush toward, anode and constitute the current! Ex.7 electrons with maximum kinetic energy of ejected electrons can be given as about OZ get. Everyone being able to pitch in when they know something for Atomic Structure chapter of the light intensity what can! E = mc2 the equivalent mass m of the electrons which are anode. And agree to the modern understanding of each chapter of Class 12 PDF document download... Then kinetic energies will rush toward, anode and may constitute the photoelectric current in circuit.! Surface may have different kinetic energies, distributed from 0 to on everyone being able to pitch when! When a light beam if light is a knowledge-sharing community that depends on intensity of the metal of board. S Physics Class 12 Physics, force on plate due to reflected photons Fr = nr ΔPr increase in variation! By Class 12 PDF in PDF format can be given as the incident beam ( figure.! An electron when it is found that the critical retarding potential is 1.3 V, find the kinetic... 0.9, Sol difficulty in the CBSE syllabus attracted Back to subjects home ; 12! Light beam if light is incident on the respective subtopics the exhaustive content provided for each of these electrons be! 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