# Introductory Physics – Question Paper 2015 | BSc. Environmental Management (PU) 1st SEM

## Pokhara University Level: Bachelor | Semester: Fall | Year: 2015 Programme: B.Sc. Environmental Management Course: Introductory Physics

Full Marks: 100 | Pass Marks: 45 | Time: 3 Hrs
Candidates are required to give their answer own words as far as practicable. The figures in the margin indicates full marks.

Attempt all the questions:

1. (a) Define the terms electric current and current density. Derive an 9 expression of drift velocity in terms of current density. 
(b) A ball is dropped from a height of 20m and rebounds with a velocity which is ¾ of the velocity with which it hits the ground. What is the time interval between the first and second bounces? 
2. (a) Define the laws of radioactive disintegration. Also derive the decay equation . 
(b) Describe about the comparative study between α particles, β particles and γ rays. 
3. (a) What is Doppler’s effect? Derive an expression for the apparent frequency received by a stationary listener in still medium, when the sources is moving from the listener. 
(b) A current of 1.5 A is passed through a wire of length 1m and diameter of 2mm. If the specific resistance is 2.42X10-8Ωm, find the potential defference across the ends of the wire. 
4. (a) State and prove principle of conservation of energy. 
(b) Calculate the energy in electron volt un a quantum of X-radiation of wavelength 0.15nm. (Given: h=6.62X10-34Js, c=3X10^8m/c and e=1.6X10-19C) 
5. a) Define linear, superficial and cubical expansivity. Establish relations between them. 
(b) What amount of heat energy is required to convert 20gm of ice at -10°C into steam at 100°C ? (Given: Specific heat capacity of ice=0.5cal/gm°C, specific heat capacity of water=1cal/gm°C, latent heat of ice=80cal/gm, latent heat of vaporization = 540cal/gm) 
6. a) State and prove Bernoulli’s principle. 
b) A body travels two equal distances with velocity 20m/s and 30m/s respectively. What will be its average velocity? 
7. Write short notes on any two: [5X 2]
a) Radiation Hazards and safety precautions
b) Global warming and green house effect
c) Noise pollution, consequences and its controlling measures
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