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Roll No. ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ Total No. of Pages : 03
Total No. of Questions : 18
B.Tech. (Electrical Engg.) (2018 & Onwards) (Sem.-1,2)
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OPTICS & MODERN PHYSICS
Subject Code : BTPH-102-18
M.Code : 75354
Time : 3 Hrs. Max. Marks : 60
INSTRUCTIONS TO CANDIDATES :
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- SECTION-A is COMPULSORY consisting of TEN questions carrying TWO marks each.
- SECTION -B & C have FOUR questions each.
- Attempt any FIVE questions from SECTION B & C carrying EIGHT marks each.
- Select atleast TWO questions from SECTION - B & C.
SECTION-A
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Write briefly :
- Mention the essential characteristics of a medium supporting the propagation of mechanical waves.
- What do you understand by impedance matching?
- Make a comparison between Fresnel and Fraunhofer diffraction.
- State Huygens’s principle.
- Differentiate between spontaneous and stimulated emission.
- State Uncertainty principle and mention its different forms.
- Define Expectation Value.
- What is Born interpretation of probability densities?
- What is the origin of energy bands?
- Differentiate VI characteristics of a p-n junction in forward and reverse bias.
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Firstranker's choice
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SECTION-B
- a) Explain free vibrations, damped vibrations, forced vibrations and resonance, giving one example of each. 3
b) Discuss the theory of forced harmonic oscillations. How does sharpness of resonance depend on damping? 5 - a) Derive the equation for transverse waves on a string and discuss reflection and transmission of such waves at a boundary. 4
b) Derive the equation for longitudinal waves on a string and discuss reflection and transmission of such waves at a boundary. 4 - a) Derive the expressions for reflectance and transmittance when an EM plane wave is incident normal at an interface. 5
b) Define these: Fresenel’s equations, Brewster’s angle and total intemal reflection. 3 - a) Explain the construction, working and energy diagram of Ruby laser. 5
b) Make a comparison between solid state lasers and gas lasers in terms of their advantages and limitations. 3
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SECTION-C
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- Using Uncertainty principle, prove the ;
a) Non-existence of electron in the nucleus 4
b) Radius of Bohr’s first orbit 4 - a) Solve time-independent Schrodinger wave equation for a linear harmonic oscillator to derive expressions for its eigen functions and eigen-energy values. 5
b) Noamilse the wave function 3--- Content provided by FirstRanker.com ---
Y (x) =0 outside the box of'size 1
¥ (x)= A sin kx for 0<x<l
Where k= rt/1 - a) Using Bloch’s theorem write the solutions for a wave function in a periodic potential. 6
b) Write the limitations of free electron theory of metals. 2 - a) Distinguish between metals, semiconductors and insulators on the basis of their energy band diagrams. 3
b) Differentiate between intrinsic and extrinsic semiconductors. 2
c) Discuss the dependence of Fermi level on carrier-concentration and temperature. 3
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NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any page of Answer Sheet will lead to UMC against the Student.
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This download link is referred from the post: PTU B.Tech Question Papers 2020 December (All Branches)
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