CSIT 1st Semester
Physics Board Question Paper 2080 Old Course

PHY 118-2080 ✡
Tribhuvan University
Institute of Science and Technology
2080
✡
Bachelor Level/First Year/First Semester/Science
Computer Science Information Technology (PHY 118)
(Physics)
(Old Course)
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 Answer Questions
Attempt any Two question.
[2x10=20]
1.

What do you mean by the pn (p and n refers to hole and free electrons) junction? Use Fermi-Dirac statistics and Maxwell-Boltzmann distribution to show the flow of electrons from n to p is equal to the flow from p to n. Discuss the mobility of holes and electrons in the pn junction.

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.

3.

Describe Frank Hertz experiment. Why do we need to heat up the mercury in Franck-Hertz experiment? How does temperature affect the Franck-Hertz experiment? Interpret the result of the experiment.

Section B

Attempt any Eight questions

[8x5=40]
4.

Discuss magnetic dipole moment. What is its effect on atom? and on molecules? Explain.

5.

Explain the process of semiconductor purification by describing the zone refining and single crystal growth.

6.

Explain the construction and working of TTL gate.

7.

You are spinning a 5 kg solid ball with a radius of 0.50 m. If it is accelerating at 4.0 radian/s2, what torque are you applying?

8.

An electron is placed midway between two fixed charges, q1= 2x10-10 C and q2= 6x10-10 C. If the charges are 1 m apart, what is the velocity of the electron when it reaches a point 10 cm from q2?

9.

What is the wavelength of an electron moving at 5.31 x 106 m/sec? [Given: mass of electron = 9.11 x 10-31 kg and h = 6.626 x 10-34 Js.]

10.

What is the probability of finding a particle in a well of width a at a position a/2 from the wall if n = 1, 2, and 3. The normalized wavefunction is ψ(x, t) = (2/a)1/2 sin((n𝜋x)/a) e-iEt/ℏ

11.

Sodium metal crystallizes in the bcc structure with an edge length of unit cell 4.29 x 10-8 cm. Calculate the atomic radius of sodium metal.

12.

The output of a digital circuit (y) is given by this expression:
y = (B̄D + C̄A)(B̄A)
Where A, B, C and D represent inputs. Draw a circuit of above equation using OR, AND and NOT gate and hence find its truth table.