## PH6151 PHY Important Questions

Anna University Regulation 2013 Computer Science & Engineering (CSE) PH6151 PHY Important Questions for all 5 units are provided below. Download link for CSE 1st SEM PH6151 ENGINEERING PHYSICS Answer Key is listed down for students to make perfect utilization and score maximum marks with our study materials.

### PH6151 PHY Important Questions

UNIT I – CRYSTAL PHYSICS

PART A

1. What is meant by Unit cell?
It is the smallest geometrical structure of a solid from which the entire crystal structure can be constructed by repetition in three-dimension.
2. What are the Lattice parameters for a unit cell?
The intercepts on the axes a, b and c and interfacial angles α, β and γ are called lattice parameters of a unit cell.
3. Name the seven Crystal Systems.
a) Cubic b) Tetragonal c) Orthorhombic d) Monoclinic e) Triclinic f) Rhombohedral g) Hexagonal
4. What are Bravias Lattices?
There are only 14 ways of arranging points in space such that the environment looks same from each point. i.e., there are 14 possible types of space lattices out of the seven crystal systems. These 14 space lattices are called as Bravais lattices.
5. Define Co-ordination number.
It is the number of nearest neighbor atoms that an atom has in the given crystal structure.
6. Write the uses of Graphite?
¾ It is used as a lubricant in lathe, air compressors, railway truck- joints open gears, cast iron bearings, general machine shop works. ¾ When the graphite is mixed with the oil it is called oildag which is used in internal combustion engines. ¾ When the graphite is mixed with the water it is called aquadag which is used as an oil free lubricant in food stuff industries.
7. Classify the crystal growth techniques.
The various crystal growth techniques are ¾ Solution growth ¾ Melt growth ¾ Vapour growth

8. Name the two important Melt growth techniques.
The two important melt growth techniques are Czochralski technique Bridgman technique
9. Write a short note on Crystal growth from melt.
Melt growth is the process of crystallization by fusion and resolidification of the starting materials.
10. What are the advantages of Czochralski method?
¾ Growth from free surface ¾ Growth of large oriented single crystals ¾ Convenient chemical composition ¾ Control of atmosphere
11. What are the limitations of Bridgman Technique?
¾ Confinement of crystals ¾ Crystal perfection is not better than that of the seed ¾ No visibility
Advantages ¾ Halogen based VPE produces high pure single crystal layers with limited defects. ¾ Hyride based VPE allows proper control over the ratio of group III to group V vapor phase species. Disadvantages ¾ Higher growth temperatures results in higher impurity diffusion. So uniform distribution of impurities cannot be obtained.
13. A unit cell has the dimensions a=b=c = 4.74 Å and α=β=γ=60°.What is its crystal structure. The unit cell is Trigonal or Rhombohedral.
14. What are Miller Indices?
Miller indices are defined as the reciprocal of the integers made by the plane on the crystallographic axes which are reduced to smallest numbers.
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