## March 9, 2010

### PH1154-PHYSICS-II Question Papers

BE/B.TECH DEGREE EXAMINATION,MAY/JUNE 2006
Second Semester Electronics and Communication Engineering
PH1154-PHYSICS-II Question Papers
(Regulations 2004)Time:3hrs Maximum:100 marks

PART A-(10X2=20 marks)

1.Distinguish between conductor and insulator based on band theory of crystals.
2.What are bound and free electrons?
3.What is drift current in a semiconductor and give tis relation using mobility of electrons and holes?
4.Calculate the critical current density for 1mm diameter wire of lead at 4.2K.A parabolic dependance of Hc upon temperature may be assumed.Given: Tc=7.18K and Ho=6.5X10^4 A/m.
5.Define “dielectric loss” and “dielectric breakdown”.
6.Differentiate between direct in indirect bandgap semiconductors with diagram and example.
7.Name any four aspects of soft and hard magnetic materials.
8.What are the properties of ferrites?
9.Compare between Czhchrolski's and Bridgeman's technique on bulk crystal growth.
10.What are “ion plating” and “cathode sputtering” in thin film technology?

PART B-(5X16=80 marks)

11.(i)Describe the frequency and temperature effects on polarisation.(8)
(ii)Explain with diagram dynamic scattering and twisted nematic crystal display.(6)
(iii)Distinguish between fluorescence and phosphorescence.(2)
12.(a)(i)Show that the path of motion of an electron under perpendicular electric and magnetic field is a cycloid.(8)
(ii)Derive the electrical conductivity of metal based on classical free electron theory.(6)
(iii)Find the speed and kinetic energy of an electron after it has moved through a potential difference of 1000V.(2)
Or
(b)(i)Derive an expression for density of states of a metal.(8)
(ii)Derive Richardson-Dushman equation for electronic work function in metals.(8)
13.(a)(i)Derive the relation for carrier concentration in n-type semiconductor.(8)
(ii)Explain generation and diffusion of charge carriers in semiconductors.(8)
Or
(b)(i)Explain BCS theory of superconducting materials.(6)
(ii)Distinguish between type I and type II superconductors.(6)
(iii)Describe high temperature superconductors.(4)
14.(a)(i)Explain the hysteresis curve on the basis of domain theory.(6)
(ii)In magnetic material the field strength is found to be 10^6 A/m.If the magnetic susceptibility of the material
is 0.5X1 0^-5,calculate the intensity of magnetisation and flux density in the material.(2)
(iii)Distinguish between dia and paramagnetism.(8)
Or
(b)(i)How will you record and reproduce the information from magnetic tape?
(ii)Explain magnetic bubble storage device.(8)
15.(a)(i)Describe the principle ,construction and working of liquid phase epitaxy.(8)
(ii)Show the five steps involved in fabrication of monolithic IC.(8)
Or
(b)(i)Explain the two basic process involved in thick film technology.(6)
(ii)Draw the cross section of monolithic base diffused resistor and explain it.(6)
(iii)Explain metal N-type semiconductor contact.(4)

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