physics pass 6th sem 2015 previous year Bsc question paper | Assam University
TDC Even Semester Exam 2015
PHYSICS
( Pass )
6th Semester
Paper No. PHSP—601
(Crystallography and Electronics)
Fuli Marks: 35
Pass Marks-: 12
Time: 2 hours
The rigures in the margin indicate full marks
for the questions
Answer five questions, taking one from each Unit
UNIT-I
1.a) Distinguish between amorphous and crystalline materials.
(b) Give the unit cell specification for the following crystals
(i) Triclinic
(ii) Tetragonal
(iii) Monoclinic
2. (a) Explain primitive cell.
(b) Define Miller indices. A plane makes inte-cepts of 1 A, 2 A and 3 A on the crystallographic axes of a orthorhombic crystal with a: b: c =3 : 2: 1. Determine the Miller indices of this plane. 1+3
UNIT—Il
3. Write the theory of formation of lane spots during X-ray diffraction.
4. (a) State arid explain Bragg’s law.
(b) Explain how the lattice parameters for cubic lattices can be measured.
UNIT—Ill
5. (a) Explain the phenomenon of thermionic emission.
(b) Deduce Richardson’s equation of therniionic emission.
6. (a) Briefly describe the construction of a triode.
(b) Establish the relationship between triode parameters.
(c) Explain the working of a triode as amplifier.
UNIT—IV
7. (a) Name the two types of breakdowns which occur in a p-n junction diode.
(b) Explain the working of a Zener diode as a voltage regulator.
(c) An a.c. voltage of peak value 20 V is connected in series with a junction diode and load resistance of 500 2 Assuming the diode to be ideal, find (i) peak current through diode and (ii) peak output voltage.
8. (a) What is a transistor? Draw the symbols of n-p-n and p-n-p transistors.
(b) With necessary circuit diagram, discuss the input and output characteristics of a transistor in CE configuration.
UNIT—V
9. (a) What is an oscillator? State Barkhausen criterion for osciUation.
(b) With the necessary circuit diagram, discuss the working of a tuned-collector oscillator.
10. (a) What is a logic gate?
(b) Discuss the circuit diagram of two-input AND gate using diodes and explain their working.
(c) State De Morgan’s theorem. Prove with the help of truth table.
J15—960/1276 A-15/EVEN/PHSP-601
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