QUE>Define the term (a) coloumb’s law (b)Polarisability
ANS> Coulomb’s Law : –The force between two electric charges is directly proportional to the product of the charges and inversely to the square of the distance between them.F = k[q1q2]/r2
Polarizability usually refers to the tendency of matter, when subjected to an electric field, to acquire an electric dipole moment in proportion to that applied field.
QUE> Differentitate diamagnetic and Paramagnetic material on the basis of magnetisation
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QUE>What is magnetic permeability and magnetic susceptibility? The magnetic field strength of copper is 106 A/m. If magnetic susceptibility of copper is (-0.8 x 10), calculate flux density and, magnetisation of copper.
ANS>Magnetic susceptibility : –It is a measure of a material’s ability to become magnetized in a magnetic field. It is the ratio of magnetization density to the magnetic field intensity.χm=M/H.
Permeability : -It is defined as the ratio of the magnetic induction ‘B’ to the applied field ‘H’. OR It is the ratio of magnetic field density to magnetic field intensity. Permeability is a measure of material’s ability to support the formation of magnetic field.µ=B/H
QUE><i> What is Critical Temperature, Critical field and critical current?
ANS>Critical temperature: The temperature at which a material’s electrical resistivity drops to absolute zero is called the critical temperature or transition temperature Tc.
Critical Magnetic Field (Hc): The magnetic field required to convert the superconductor into a conductor is known as a critical magnetic field.
The critical current I c is defined as the transport current at which the flow voltage clearly appears.
<ii> A superconducting tin has a critical temperature of 3.7 K at zero magnetic field and a critical field of 0.0306 Tesla at 0 K. Find the critical field at 2 K.
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QUE> A superconducting tin has a critical temperature of 3.7 K at zero magnetic field and a critical field of 0.0306 Tesla at 0 K. Find the critical field at 2 K.
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QUE>What is Magnetostriction effect? Explain how to produce ultrasonic 06 wave using magnetostriction effect with necessary diagram.
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QUE>Write a short notes: (a) Black Body Radiation (b) p-n junction diode
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QUE>Mention four differences between Photon and electron.
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QUE>(i) Derive Rayleigh Jean’s law for the lower frequency limit of Planck’s 03 law for black body radiation.
(ii) Mention three differences between Metal,Semiconductor Insulator.
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QUE>Derive the condition for maximum and minimum intensity in case of Interference phenomena of light.
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QUE>Discuss Young’s double slit experiment for phenomena of light.
ANS> When two waves of the same frequency having a constant initial phase difference traverse simultaneously in a medium superpose each other, the resultant intensity of light is not distributed uniformly in space. This modification in intensity is called interference.
On the basis of wave theory of light, the formation of dark and bright fringes can be explained. The cylindrical wavefronts starting from S falls on S1 and S2. According to Huygens principle, S1 and S2 become center’s of secondary wavelets, i.e., two cylindrical wave fronts emerge out from S1 and S2. Their radii increase as they move away from S1 and S2 so that they superimpose more and more on each other. At points where crest (or trough) due to one falls on a crest (or trough) due to the other, the resultant amplitude is the sum of the amplitudes due to each wave separately. The intensity, which is proportional to the square of the amplitude, at these points is therefore a maximum. This is the case of constructive interference. At points where a crest due to one falls on a trough due to the other, the resultant amplitude is the difference of the amplitudes due to separate waves and the resultant intensity is a minimum. This is the case of destructive interference.
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QUE>Explain the working principle of Solid State Laser (Nd-YAG laser) with necessary energy level diagram.
ANS>Construction:
Nd-YAG Laser This laser system has two absorption bands (0.73 m and 0.8 m)
Optical pumping mechanism is employed.
Laser transition takes place between two laser levels at 1.06 mm.
A Nd: YAG rod and a krypton flash lamp are enclosed inside an ellipsoidal reflector. In order to make the entire flash radiation to focus on the laser rod, the Nd: YAG rod is placed at one focal axis and the flash lamp at the other focal axis of the ellipsoidal reflector.
Working:
Energy level Diagram The flash lamp is switched on. The optical pumping excites the Nd3+ ions from the ground energy state E0 to the higher energy level E3 and E4 by absorbing radiations of wavelength 0.80 μm and 0.73 pm, respectively. The energy-level diagram is shown in Figure 6.5. The excited Nd3+ ions then make a transition from these energy levels. The transition from the energy level E4 to E2 is a non-radiative transition. The state E2 is the metastable state. Upon continuous excitation, population inversion of Nd3+ ions is achieved at the metastable state E2. Any of the spontaneously emitted photon will make the excited Nd3+ ions to undergo a transition between E2→E1 state. Thus, during this transition the stimulated photon is generated. The photons travelling parallel to the resonator axis experience multiple reflections at the mirrors. As a result, the transition E2→E1 yields an intense and coherent laser beam of wavelength 1.064 um. These lasers give beam continuously. The Nd3+ ions then make a transition between E1→E0 which is a non-radiative transition
QUE>Derive the Clausius Mossetti Equation for non polar dielectric.
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