BSc Physics SEM III 2017 2018 2018 Physics Paper III Question Paper - Mumbai University | munotes

Questions asked in this paper

• (2) Figures to the right indicate maximum marks

1. Q1 A) Select the correct option 12 marks
   • 1) A single optical fiber have the core and the cladding refractive indices of 1.5 and 1.4 respectively. The critical angle of the fiber is
   • a) d) none of these
   • 2) The process of achieving greater population of higher energy state as compared to lower energy stateis known as
   • a) Stimulated emission b) Population inversion c) Induced absorption d) none of
   • 3) is movement of particle of matter due to its own kinetic energy from region of higher concentration to the region of lower concentration
   • 4) is pressure in atmosphere which is needed in opposite direction to stop the entry of solvent from dilute solution to concentrated solution
   • 5) Which of the following statement is wrong about a semiconductor?
   • a) There are no free electrons at 0 K There are no free electrons at any temperature
   • c) The number of free electrons increases with temperature
   • d) The number of free electrons is less than that in a conductor
   • 6) The susceptibility of paramagnetic material 1s
   • a) positive and small. b) positive and large c) negative zero
2. Q1 B) Answer in one sentence 3 marks
   • 1) Define sound absorption coefficient of a material
   • 2) State any two uses of LASER?
   • 3) Define magnetic flux density
3. Q1 C) Fill in the Blank 5 marks
   • 1) technology that uses glass or plastic fibers to transmit data or information in the form of light pulsesis called
   • 2) LASER stands for Light Amplification by emission of radiation
   • 3) Golgi apparatus participates in cell wall formation and secretion. This statement is
   • Q. P. Code: 20520
   • 4) In semiconductor, the impurity added to an intrinsic semiconductor is
   • 5) The unit of magnetic induction is
4. Q2 A) Attempt any one 8 marks
   • 1) What is Holography? Explain the construction and reconstruction of hologram with
   • 2) Explain the following factors affecting the acoustic quality of building
5. Q2 B) Attempt any one 8 marks
   • 1) Explain the principle of optical fiber. Write its applications in communication and
   • 2) With a neat energy level diagram explain the construction and working of He-Ne
6. Q2 C) Attempt any one 4 marks
   • 1) For an empty assembly hall of size 20 x 15 x 10 cubic meter with total surface area 1300 m? and average absorption coefficient 0.106. Calculate reverberation time
   • 2) The silica optical fiber with a core refractive index of 1.50 and a cladding refractive index of 1.47. Determine critical angle at core-cladding interface and numerical aperture of the fiber in air. [refractive index for air (no) = 1]
7. Q3 A) Attempt any one 8 marks
   • 1) Explain Action potential and its propagation in cells/neurons
   • 2) What is viscosity? Give its units. Explain any one method to determine viscosity and factors effecting viscosity
8. Q3 B) Attempt any one 8 marks
   • 1) Explain Osmosis and show how it is different from Diffusion. What is Osmotic
   • 2) Explain surface tension based on molecular theory. Discuss factor effecting surface Attempt any one (04)
   • 1) Draw neat diagram and explain Electrical Properties of Cell
   • 2) Draw neat diagram and explain Prokaryotic Cell
9. Q4 A) Attempt any ONE 8 marks
   • 1) With the help of energy band diagram, explain how materials are classified as conductors, insulators and semiconductors
   • Q. P. Code: 20520
   • 2) Write a note on: a) Diamagnetic materials b) Paramagnetic materials
10. Q4 B) Attempt any ONE 8 marks
    • 1) Write a note on : a) Metals and alloys b) Ceramics c) Polymers d) Composites
    • 2) Explain hysteresis curve of ferromagnetic materials on the basis of domain theory
11. Q4 C) Attempt any ONE 4 marks
    • 1) Find the relative permeability of ferromagnetic material if a magnetic field of strength 220 A/m produces magnetization of 3300 A/m in it
    • 2) A metal wire has a resistance of 2.52 Q at If its temperature coefficient of resistance is 3.8 X find the resistance of wire at Attempt any Four (20)
    • 1) Explain the following properties of LASER light in brief. a)intensity b) directionality
    • 2) index fiber hasa numerical aperture of 0.26, a core refractive index of 1.5 and core diameter of 100 Calculate the refractive index of cladding and acceptance angle of the fiber in air
    • 3) Explain Diffusion mechanism and factors affecting rate of Diffusion
    • 4) Distinguish between Osmosis and Diffusion
    • 5) Give the applications of liquid crystal display
    • 6) Write a note on dielectric materials:

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