TRIBHUVAN UNIVERSITY
INSTITUTE OF SCIENCE AND TECHNOLOGY
2079 B.S.
Candidates are required to give their answers in their own words as far as practicable.
Group A
Long Answer QuestionsAttempt any Two questions.
- 1Explain fabrication of integrated circuits. Describe epitaxial growth, oxidation, oxide removal/pattern definition, doping, and interconnection.
- 2Explain the effect of external magnetic field on current carrying loops. Describe torque on current-carrying rectangular loop. Give ways of increasing torque.
- 3What do you mean by wavefunction? Discuss its significance. Set up time-independent and time-dependent Schrödinger wave equations.
Group B
Short Answer QuestionsAttempt any Eight questions.
- 4Derive expression for electrical conductivity of semiconductor in terms of impurity ionization energy.
- 5Discuss behavior of mobile negative charges in the Hall effect experiment.
- 6Set up differential equation for an oscillation of a spring using Hooke's and Newton's second law.
- 7Find energy, momentum, and wavelength of photon emitted when hydrogen atom transitions from $n=4$ to $n=2$.
- 8Oscillating block of mass $250$ g takes $0.15$ s between endpoints $40$ cm apart. Find frequency, amplitude, and force constant.
- 9Proton (charge $q=1.6 \times 10^{-19}$ C, mass $= 1.67 \times 10^{-27}$ kg) released across $100$ V potential difference. Find its final velocity.
- 10An alpha-particle is emitted with $6.8$ MeV energy. Calculate its wavelength and compare with nucleus radius ($8 \times 10^{-15}$ m).
- 11(a) Calculate Fermi energy of aluminum (density $2.73\text{ g/cm}^3$, weight $26.98\text{ g/mol}$). (b) Find effective mass if experimental $E_f$ is $11.8$ eV.
- 12Draw a circuit for $y = ((AB)' + B'A)((A+B)' + C)$ using OR, AND, and NOT gates and find its truth table.