We have the expression that relates mean kinetic energy of the nitrogen molecule with the root mean square speed as: Hence, the de Broglie wavelength of the nitrogen molecule is given as: Therefore, the de Broglie wavelength of the nitrogen molecule is 0.028 nm. Hence, a neutron beam of energy 150 eV is not suitable for diffraction experiments. (b) de Broglie wavelength of the electrons accelerated through a potential difference of 56 V. (a) At equilibrium, the kinetic energy of each electron is equal to the accelerating potential, i.e., we can write the relation for velocity (v) of each electron as: The momentum of each accelerated electron is given as: kg .Therefore, the momentum of each electron is kg. What is the radius of the circle traced by the beam, given e/m for electron equals. The wavelengths of this group show characteristic discrete radiations emitted by the atoms of the target material. (b)The minimum wavelength produced by the X-rays is given as: Hence, the minimum wavelength of X-rays produced is 0.0414 nm. The photoelectric effect takes place only when photons strike bound electrons because for free electrons energy and momentum conservations do not hold together. The excess energy is taken by recoiling electrons. There is always some probability in predicting the position and momentum of a particle. 22.Light of intensity falls on a sodium photo-cell of surface area. This in distinguish ability has many fundamental implications which you will explore in more advanced Physics courses. (a) maximum kinetic energy of the emitted electrons. Then, is coefficient of viscosity of air, r is radius of drop  and v, In fig. Find the typical de Broglie wavelength associated with a He atom in helium gas at room temperature and 1 atm pressure; and compare it with the mean separation between two atoms under these conditions. It is denoted by (V, Mathematically, stopping potential could be expressed as. prove wave nature of radiations. i.e., each equation contains both particle concepts (mv & E) & wave concepts (λ & ν). It proved that Photoelectric current, which is number of photoelectrons flowing per unit time, is directly proportional to the intensity of incident light, As the positive potential of collector rises, photoelectric current rises for a certain period of time because the electrons emitted experience a strong attractive force by the collector. Dual Nature Of Radiation And Matter Photoelectric emission is an instantaneous process, meaning there is no time lag between the incident light and the emission of free electrons (photoelectrons). Since the wavelengths of an electron and a photon are equal, both have an equal momentum. ), when illuminated with light of high frequency (ultraviolet, violet, etc.) 26.The wavelength of a probe is roughly a measure of the size of a structure that it can probe in some detail. Why is there an energy distribution of photoelectrons? Colour is yellowish-green for soda glass and greyish-blue for lead glass. were performed by Millikan, who, using his own value of e (from the oil-drop experiment) confirmed Einstein’s photoelectric equation and at the same time gave an independent estimate of the value of h.]. (corresponding to energy maximum) = hc/Ve where V is the voltage applied. These radiations are most energetic and most penetrating. Physicswallah Assignment. Ans. 6.The wavelength of light from the spectral emission line of sodium is 589 nm. This structure was first probed in early 1970’s using high energy electron beams produced by a linear accelerator at Stanford, USA. Since  so electron being lighter will have more wavelengths. Hence, we assume the dual nature of light. Calcium sulfide and barium sulphide, after absorbing sunlight, produce blue phosphorescence for some time. If we take an electron, mass=9.1 X 10-31 kg, moving with the speed of light (3 X 108 m/s). The phenomenon is called fluorescence. Each energy quantum has a value equal to, These specific packets of quanta of energy are known as photons, The above equation is known as Einstein’s photoelectric equation, Since saturation current is just a maximum value of photoelectric current, saturation current gets higher with increasing intensity of incident light. 4. The wavelength of X-rays emitted is minimum corresponding to the electron which hits the target with maximum speed. For 1 marker and MCQ for class 12 boards, conceptual questions from these topics as well as threshold frequency and wave function can be asked. 2. Dual Nature of Radiation and Matter Class 12 Notes Chapter 11 1. This strongly suggests that the electrons have a wavelength λ associated with them and that the. Therefore, the radius of the circular path is 22.7 cm. 9, Laxmi Nagar Delhi-110092. = maximum velocity obtained by photoelectrons, ν = frequency of incident light i.e., photon. Concise NCERT Class 12 Revision Notes Physics Chapter 11 Solution will help you to learn and understand the above-mentioned topics. The fluorescence of barium sulphate as well as uranium oxide gives out green light when illuminated with ultraviolet or violet light. . b. Click here. & same wavelength as that of incident X-rays. Hg entire tube is dark (Crooke’s dark space) except the glass wall behind anode. Ans.Kinetic energy of the electron, Ek= 120 eV. Whenever radiation interacts with the matter, it displays particle like properties in contrast to the wavelike properties (interference and diffraction), which it exhibits when it propagates. This change in wavelength i.e. (a) Quarks inside protons and neutrons are thought to carry fractional charges [(+2/3)e; ( – 1/3)e]. And the electrons released due to photoelectric effect are called photoelectrons, Evacuated tube consist of photosensitive plate (emitter) and the metal plate (collector), so that electrons could freely flow from emitter to collector without any air resistance, Photosensitive plate (emitter) to absorb visible light and emit electrons, Metal plate (collector) to receive electrons emitted from the emitter, thus constituting a photoelectric current flow from collector plate to the emitter plate (opposite to the flow of electrons), Monochromatic light of short wavelength (meaning high frequency), Battery to accelerate emitted electrons through a potential difference, Voltmeter to measure the potential difference between the emitter and the collector plates due to photoelectric current flow. Similarly intestine and digestive system abnormalities are also detected by X-rays. How are their kinetic energies related to each other? Fluorescent materials emit light only so long as light is incident on them. 20.A mercury lamp is a convenient source for studying frequency dependence of photoelectric emission, since it gives a number of spectral lines ranging from the UV to the red end of the visible spectrum. Why do they not show up in Millikan’s oil-drop experiment? Free PDF Download of CBSE Physics Multiple Choice Questions for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter. (a) An X-ray tube produces a continuous spectrum of radiation with its short wavelength end at 0.45 .What is the maximum energy of a photon in the radiation? What will be the new wavelength when the accelerating potential is increase to 4V? Wavelength of the emitted sodium light, = 589 nmm. Space, negative glow, Crooke ’ s wavelength for a given photosensitive surface the. 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