Questions
Syllabus
Qns. By Syllabus

Semester

Subject

Year

Tribhuwan University

Institute of Science and Technology

2077

Bachelor Level / First Year / First Semester / Science

B.Sc in Computer Science and Information Technology (PHY118)

(Physics)

Full Marks: 60

Pass Marks: 24

Time: 3 Hours

Candidates are required to give their answers in their own words as for as practicable.

The figures in the margin indicate full marks.

Section A

Long Answers Questions

Attempt any TWO questions.
[2*10=20]
1.
Explain RTL and TTL gates. How memory and clock circuits can be made by using these gates? Explain how they work? [10]
2.
Set up differential equation for an oscillation of a spring using Hooke's and Newton's second law. Find the general solution of this equation and hence the expressions for period, velocity and acceleration of oscillation. [10]
3.
Describe Frank-Hertz experiment. Interpret how the results of this experiment advocate atomic model proposed by Bohr? [10]
Section B

Short Answers Questions

Attempt any Eight questions.
[8*5=40]
4.
Discuss magnetic dipole moment. What is its effect on atom and on molecules? Explain. [5]
5.
Describe the following process of IC production: (a) Oxidation, (b) Pattern definition, and (c) Doping [5]
6.
Explain the construction and bipolar junction transistor (BJT). [5]
7.
A roulette wheel with moment of inertia I=0.5 kgm2I = 0.5\ \mathrm{kgm^2} rotating initially at 2 rev/sec coasts to a stop from the constant friction torque of bearing. If the torque is 0.4 Nm, how long does it take to stop? [5]
8.
Two large parallel plates are separated by a distance of 5 cm. The plates have equal but opposite charges that create an electric field in the region between the plates. An α\alpha particles (q = 3.2×10−273.2\times10^{-27} kg) is released from the positively charged plate, and strikes the negatively charged plate 2×10−62\times10^{-6} sec. later. Assuming that the electric field between the plates is uniform and perpendicular to the plates, what is the strength of the electric field? [5]
9.
The energy gap in silicon is 1.1 eV, whereas in diamond it is 6eV. What conclusion can you draw about the transparency of the two materials to visible light (4000A∘to7000A∘4000 A^{\circ} to 7000 A^{\circ})? [5]
10.
Find the truth table for the circuit shown in the figure. What logic function will the circuit perform if the constant +5 V input to the first two gates is changed to ground potential? [5]
11.
In neutron spectroscopy a beam of monoenergetic neutrons is obtained by reflecting reactor neutrons from a beryllium crystal. If the separation between the atomic planes of the beryllium crystal is 0.732 A∘A^{\circ}, what is the angle between the incident neutron beam and the atomic planes that will yield a monochromatic beam of neutrons of wavelength of wavelength 0.1 A∘A^{\circ}? [5]
12.
What is the probability of finding a particle in a well of width aa at a position a4\frac{a}{4} from the wall if n=1n = 1, if n=2n = 2, if n=3n = 3. Use the normalized wavefunction ψ(x,t)=(2a)12sin⁡(nπxa)e−iEtℏ\psi(x,t) = \left(\frac{2}{a}\right)^{\frac{1}{2}} \sin\left(\frac{n\pi x}{a}\right) e^{-\frac{iEt}{\hbar}}.
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