Questions
Syllabus
Qns. By Syllabus

Semester

Subject

Year

Tribhuwan University

Institute of Science and Technology

2075

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 the process of semiconductor purification by describing the terms Zone refining, single crystal growth, and scheme of IC production. Give an account of electronic component fabrication on a chip. [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.
Discuss magnetic dipole moment. What is its effect on atom and on molecules? Explain. [5]
4.
Describe Frank Hertz experiment. Discuss its result and outline limitations. [10]
Section B

Short Answers Questions

Attempt any Eight questions.
[8*5=40]
5.
Explain Bloch theorem. Discuss its use in Kronig-Penney model and hence in band theory. [5]
6.
Explain the construction and working of bipolar junction transistor (BJT). [5]
7.
A large wheel of radius 0.4 m and moment of inertia 1.2 kgm2kgm^2, pivoted at the center, is free to rotate without friction. A rope is wound around it and a 2-kg weight is attached to the rope. When the weight has descended 1.5 m from its starting position (a) what is downward velocity? (b) what is the rotational velocity of the wheel? [5]
8.
An electron is placed midway between two fixed charges, q1=2.5∗10−10Cq_1 = 2.5*10^{-10} C and q2=5∗10−10Cq_2 = 5*10^{-10} C. If the charges are 1 m apart, what is the velocity of the electron when it reaches a point 10 cm from q2q_2? [5]
9.
Assuming that atoms in a crystal structure and arranged as close-packed spheres, what is the ratio of the volume of the atoms to the volume available for the simple cubic structure? Assume a one atom basis. [5]
10.
The output of a digital circuit (y)(y) is given by this expression:y=(CB+C‾A)(B‾A)y = (CB + \overline{C}A)(\overline{B}A) where AA, BB and CC represent inputs. Draw a circuit of the above equation using OR, AND and NOT gate and hence find its truth table. [5]
11.
A small particle of mass 10−6gm10^{-6} gm moves along the x axis; its speed is uncertain by 105m/sec10^5 m/sec. (a) what is the uncertainty in the x coordinate of the particle? (b) Repeat the calculation for an electron assuming that the uncertainty in its velocity is also 105m/sec10^5 m/sec. use the known values for electrons and Planck's constant. [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)=(2a)1/2sin⁡(nπxa)e−iEtℏ\psi(x) = \left(\frac{2}{a}\right)^{1/2} \sin\left(\frac{n\pi x}{a}\right) e^{-\frac{iEt}{\hbar}} [5]