Engineering Physics-II. Question Bank

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1 Engineering Physics-II Question Bank

2 Unit No I Short Answer Type 1. What are de-broglie waves? 2. Discuss few properties of matter waves. 3. What do you mean by phase velocity and group velocity? 4. What is the relation between phase velocity and group velocity? 5. What is uncertainty principle? 6. What is a wave packet? 7. Define wave function. 8. What is physical significance of a wave function? 9. What do you mean by eigen value and eigen function? 10. Discuss the result of one dimensional box. 11. Explain single step potential barrier. 12. What is tunnel effect? Numerical Problems 1. Calculate the de-broglie wavelength associated with a proton moving with a velocity equal to 1/20 th of velocity of light. (UPTU 2008) 2. Determine the velocity and kinetic energy of a neutron having de-broglie wavelength 1 A o. Given that mass of neutron 1.67 X kg and h = 6.63 X J-s. (UPTU 2006) 3. What is the de-brogliewavelength of an electron which has been accelerated from rest through a potential difference 100V. (UPTU 2001) 4. A particle of rest mass m 0 has a kinetic energy K. Show that de-broglie wavelength is { } (UPTU 2005) 5. An electron has de-broglie wavelength 2 X m. Find the kinetic energy. Also find the phase velocity and group velocity of its de-broglie waves. (UPTU 2008) 6. Kinetic energy of an electron is 4.55 X J. Calculate velocity, momentum and wavelength of the electron. (UPTU 2009) 7. A proton is moving with velocity 2 X 10 8 m/s. Find the wavelength of matter wave associated with it. (UPTU 2003) 8. Show that the de-broglie wavelength for a material particle of rest mass m o and charge q accelerated from rest through a potential difference V is { } (UPTU 2001) 9. Show that phase velocity of de-broglie waves associated with a moving particle having rest mass m o is given by [ ] (UPTU 2005)

3 10. If the uncertainty in the location of a particle is equal to its de-broglie wavelength, what is the uncertainty in the velocity? (UPTU 2008 C.O.) 11. Calculate the smallest possible uncertainty in the position of an electron moving with velocity 3 X 10 7 m/s. (UPTU 2006,2003) 12. An electron has a speed 600 m/s with an accuracy of 0.005%. Calculate the uncertainty in the position of the electron. (UPTU 2008) 13. Calculate the uncertainty in the velocity of the electron which is confined in a box having dimension 10 A 0. (UPTU2006) 14. If an excited state of a hydrogen atom is 2.5 X µ sec, what is the uncertainty in energy of this state? h = 6.63 X J-s (UPTU 2005) 15. Find the energy of an electron moving in one dimension in an infinitely high potential box of width 10 A 0.(m e =1.67 X kg & h = 6.63 X J-s) (UPTU 2001,5,6,7) 16. A particle of mass m is represented by in the range 0 and elsewhere. Find the normalized form of the wave function. (UPTU 2002,4,5,6,7) 17. Find the probability of finding a particle trapped in a box of length L in the region from 0.45 L to 0.55 L for the ground state and the first excited state. (UPTU 2008) 18. Calculate the energy difference between ground state and first excited state for an electron in one dimensional rigid box of length 10-8 cm. (UPTU 2006) Long Answer Type 1. What are de-broglie waves? Show that wavelength associated with a particle of mass m and kinetic energy E is given by (UPTU 2002,2007) 2. Distinguish between wave velocity and group velocity of a wave packet. Prove that V P V g = c 2 (UPTU 2009) 3. What is uncertainty principle? Apply this to prove the non-existence of electron inside the nucleus. (UPTU 2001,4,6,7,8) 4. Derive time dependent and time independent Schrodinger wave equation. (UPTU 2001,2,3,4,6) 5. A particle is in motion along a line between x = 0 and x = a with zero potential energy. At points for which x < 0 and x > 0, the potential energy is infinite. Solve Schrodinger equation, obtain energy eigen values and normalized wave for the particle. (UPTU 2003,8)

4 Unit No II Short Answer Type 1. What is superconductivity? 2. What is Meissner effect? 3. Explain the salient features of BCS theory. 4. What is persistent current? 5. Explain the effect of isotope on superconductors. 6. Write short note on high temperature superconductor. 7. Explain Maglev vehicle. 8. Define nanoscience and nanotechnology. 9. Explain the categories of nanomaterial. 10. Give two procedures for the synthesis of carbon nanotubes. 11. Give some uses of nanomaterials. 12. Explain various properties of nanomaterials. Numerical Problems 1. The transition temperature of Pb is 7.2 K. It loses its superconductivity when subjected to a magnetic field 3.3 X 10 4 A/m. Find the value of H c (0) which will allow the metal to retain its superconductivity at 0K. 2. A superconducting material has a critical temperature of 3.7 K in magnetic field of T at 0K. Find the critical field at 2K. (UPTU 2009) 3. The critical field of niobium is 10 4 A/m at 8K and 2 X 10 5 A/m at 0K. Calculate the transition temperature of the element. 4. For a specimen of superconductor, the critical fields are 1.4 X 10 5 A/m and 4.2 X 10 5 A/m respectively for temperature 14 K and 13 K respectively. Calculate the transition temperature and critical field at 0 K and 4.2 K. 5. Calculate the critical current which can flow through a long thin superconducting wire of diameter 10-3 m. Given H c = 7.9 X 10 3 A/m. 6. Determine the critical current and critical current density for a superconducting ring of diameter 10-3 m at temperature 4.2 K. Given the critical field for the sample is 7.18 K and critical field is 6.5 X 10 4 A/m. 7. The lead material works as superconductor at a temperature 7.26 K. If the constant characteristic field of lead material of lead material at 0K is H(0) = 8 X 10 5 A/m. Calculate the magnetic field at 5K.

5 Long Answer Type 1. What is superconductivity? Discuss the temperature dependence of resistivity in superconducting materials. 2. What do you mean by Meissner Effect? Explain how Meissner Effect prove the superconductivity to be a perfect material. 3. What are type-i and type-ii superconductors? Why are type-i superconductors poor current carrying conductors. 4. Discuss a detail description of high temperature superconductivity. 5. What are the changes in the properties that take place in a material when its size is reduced to nanoscale. Explain the reason for the change. 6. What is bucky ball? How can bucly ball be created? Where can these buclky balls be used? 7. How are single-walled carbon nonotubes (SWNT) different from multi-walled carbon nonotubes (MWNT)? 8. What do you mean by quantum dot, quantum wire and quantum well? How quantum dots are synthesized? 9. Give some important applications of nonotechnology.

6 Unit No III Short Answer Type 1. What are polar and non-polar dielectrics? 2. Define terms E, D and P. Also derive the required relation. 3. Explain loss tangent. 4. Explain ferro-electricity and piezoelectricity. 5. Discuss important applications of dielectric materials. 6. What is hysteresis loss? 7. Explain applications of hysteresis. Numerical Problems 1. The dielectric constant of He ( at 0 0 C and 1atm pressure) is Find the dipole moment induced in each helium when the gas is in electric field of intensity 100 V/m. (UPTU 2008) 2. Determine the percentage of ionic polarasability in the NaClcrystal having refractive index 1.5 and static dielectric constant Calculate electronic polarizabilty of Argon having dielectric constant at NTP and N = 2.7 x atom/ m 3. Long Answer Type 1. What are dielectrics? Define dielectric constant of a material. 2. What is local field? Obtain an expression for Clausius-Mossotti relation. 3. Define polarization in dielectrics. Explain different types of polarisability in dielectrics. 4. Discuss the frequency dependence of dielectrics. 5. Describe Langevin s theory of dia magnetism. Show that the magnetic susceptibility is negative and independent of temperature. (UPTU 2008, 2009) 6. Describe the importance of hysteresis curve. Explain residual magnetism, coercive force and hysteresis loss. (UPTU 2007) 7. Discuss different types of polarization. Describe the frequency dependence of various polarizabilities. 8. Describe Langevin s theory of diamagnetism. Show that the magnetic susceptibility is negative and temperature independent. (UPTU 2008,2009)

7 9. What are the factors responsible for hysteresis loss? Prove that area of B H curve is equal to hysteresis loss per unit volume of the specimen in one cycle. (UPTU 2006) 10. Describe the importance of hysteresis curve. How would you use the hysteresis curve for selecting the material for the construction of permanent magnet and core of transformer?

8 Unit No 1V Short Answer Type For EC, AEI and EE Branch 1. Give introduction to electrical conductivity. 2. Explain P type and N type semiconductor. 3. What is photovoltaic effect? 4. Explain the term mobility. How is it related with conductivity? 5. Plot Fermi Dirac probability function f(e) versus E at different temperatures. 6. What is cryogenics? 7. What is adiabatic demagnetization? 8. Give the construction of platinum resistance thermometer. For CS and IT Branch 9. Give the basics of semiconductor memories. 10. Describe read only memory (ROM). 11. Describe random access memory. Numerical Problems 1. Find the value of (E) for = 0.01 ev at 400 K. 2. Assuming hole concentration in silicon sample is 4.02 x atom/ m 3. Find hall coefficient? 3. An electric field of 200 V/m is applied to a sample whose hall coefficient is m 2 /coulomb. Calculate current density if the mobility of electrons is 0.36 / V-s. 4. Find the Hall coefficient of Sodium assuming BCC structure of the cell having side 4.28 A 0. (Given that number of atoms /m 3 for BCC is 2). 5. Assuming there are 5 X 10 3 atoms per cubic meter in gold, find the hall coefficient. 6. The single carrier holes in a germanium sample is 2.05 X per cubic meter, calculate the hall coefficient. 7. Calculate the resistance of a semiconductor rod of length 10 cm and cross section area /mm 2, if it is doped with a total of donor atoms at room temperature. Given that the electron mobility = 0.39 m 2 /v-s and e= 1.6 x coulomb. 8. Calculates the conductivity of intrinsic germanium from the following data: n i =2.4 x m - 3, µ e =0.39 m 2 /v-s and µ n =0.19 m 2 /v-s

9 Long Answer Type For EC, AEI and EE Branch 1. What do you mean by Fermi-level? Prove that Fermi-level in intrinsic semiconductor lies in midway in the forbidden band i.e. 2. What is Hall Effect? Derive an expression for hall coefficient. 3. What is a solar cell? Discuss in detail construction, working and applications. 4. What is Joule Thomson effect? Obtain an expression for cooling produced by this effect. 5. How cooling is produced in external refrigerant? Describe vapour compression machine. 6. What is refrigerant? Describe the cooling produced by vapour absorption machine. 7. How are low temperature produced by adiabatic de-magnetization? Give the theory. Define drift velocity, mobility and conductivity of a semiconductor. 8. Obtain an expression for the electrical conductivity of an intrinsic and extrinsic semiconductor. For CS and IT Branch 9. What is magnetic memory? Mention different types of backing storage hardware. 10. Differentiate between RAM and ROM.

10 Unit No V Short Answer Type For EC, AEI and EE Branch 1. Explain the term connector. 2. Write advantages of optical amplifier over regenerators. 3. What is a PIN diode? 4. Explain splicing. For CS and IT Branch 5. Give the properties of qubit. 6. Write short note on optical correlator. 7. Explain quantum data processing. Long Answer Type For EC, AEI and EE Branch 1. Explain the basic principle, using block diagram of fibre optic communication system. 2. Discuss the following (i) Wavelength division multiplexer (ii) Time division multiplexer 3. What is splicing. Discuss classification of splicing. 4. What is erbium doped fibre amplifier? Explain the principle of operation. 5. What do you mean by photodiode? Discuss PIN and Avalanche photodiode. For CS and IT Branch 6. What is Fourier optics? Explain Fourier transforms. 7. What is spatial light modulator? Explain the working of liquid crystal spatial light modulator (LCSLM). 8. What is quantum computing? Explain the difference between classical and quantum computing. 9. Explain the construction and reconstruction of a hologram.

Reg. No. : Question Paper Code : B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER Second Semester.

WS 20 Reg. No. : Question Paper Code : 27472 B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2015. Second Semester Civil Engineering PH 6251 ENGINEERING PHYSICS II (Common to all branches except Biotechnology