JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY, HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY, HYDERABAD B.Tech I APPLIED PHYSICS Previous Question Paper (December - 2018 - R18)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks and may have a, b, c as sub questions.
Part A
State the principle of uncertainty.
Answer
Heisenberg's uncertainty principle states that it is impossible to simultaneously determine both the exact position and the exact momentum of a particle with absolute precision. Mathematically, the product of the uncertainties is given by:
What is reverse saturation current?
Answer
Reverse saturation current is the small, constant current that flows through a p-n junction diode when it is reverse-biased. It is caused by the drift of minority charge carriers across the junction and is independent of the applied reverse voltage but highly sensitive to temperature.
Write any two characteristics of PIN photodiode.
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How laser beam achieves coherence?
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Why susceptibility of diamagnetic materials is negative.
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What is a blackbody? State Planck’s hypothesis.
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Explain Fermi level dependence on carrier concentration.
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A light emitting diode is made of GaAsP having a band gap of 1.9 eV. Determine the wavelength of the radiation emitted.
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Differentiate graded index fibres from step index fibres.
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Write a short note on piezoelectric materials.
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Part B
Derive one-dimensional time–independent Schrodinger wave equation for an electron.
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Calculate the velocity and kinetic energy of an electron of wavelength 1.66 Å.
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Explain Compton effect and derive expression for Compton shift.
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X-ray photon wavelength 0.3 Å is scattered through an angle 45 degrees by a loosely bound electron. Find the wavelength of scattered photon.
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With the help of schematic diagram, explain construction and principle of operation of bipolar junction transistor.
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Discuss any three applications of Hall effect.
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With neat plots describe V-I characteristics of a Zener diode in both biasing conditions.
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Explain the formation of potential barrier across the p-n junction.
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What are photodiodes? Explain working principle and structure of Avalanche photodiode.
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Explain recombination mechanism in semiconductors.
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Explain with neat diagram, the construction and working of solar cell. State few disadvantages of solar cell.
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With relevant plots, explain V-I characteristics of a solar cell.
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Derive the relationship between Einstein’s coefficients and explain their physical significance.
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Explain the applications of lasers in medicine.
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Derive an expression for acceptance angle for an optical fibre. How is it related to numerical aperture?
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Find the numerical aperture and acceptance angle of a fibre of core index 1.4 and fractional refractive indices 0.002.
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Explain the term internal field. Derive an expression for internal field in the case of one dimensional array of atoms in dielectric solids.
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Deduce Claussius-Mossotti relation for dielectrics.
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Classify the magnetic materials based on atomic point of view.
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State and explain Ampere’s circuital law.
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