SPSC 2014 B.Sc Forestry Course 2014-16 Selection Exam — Physics Paper

B.Sc Forestry Course 2014-16 Selection Exam — Physics. Wednesday 13 August 2014, 02:00 to 05:00 pm · Maximum marks 200. Attempt any SIX questions in all, selecting at least THREE questions from each Section. Question No. 01 is compulsory and carries thirty marks; each of the remaining questions carries equal marks.

1. 1Section I — Complete the following blanks with correct answers: (i) Dot product of force and distance gives ______. (ii) Newton's first law of motion is also called the law of ______. (iii) Fundamental source of electromagnetic wave is ______. (iv) First law of thermodynamics is also called the law of ______. (v) Transistor is basically used for ______ purpose. (vi) Write energy equation of nuclear fission ______. (vii) Net capacitance of parallel combination of two capacitors C1 and C2 is equal to ______. (viii) The wave length of ______ is of the order of separation between two atoms in a solid crystal. (ix) Degree per second is the unit of ______. (x) A generator provides electrical energy by the principle of ______. (xi) Einstein's mass and energy relation is ______. (xii) The real gases obey gas Laws at high temperature and ______. (xiii) The ratio of power output to power input in a transformer is called ______. (xiv) Electric fan works on the principle of an electric ______. (xv) The change of substance from solid to liquid state without rise of temperature is known as ______.

2. 2Section I — (a) Distinguish between scalar and vector physical quantities and give example of each. (b) How will you find that two vectors A and B are (i) parallel to each other (ii) perpendicular to each other? (c) If A = −2i + 3j − 4k and B = 3i − 4j + 5k, find out vector C = A × B and D = A · B. Also find out magnitude of vector D. (d) One of the rectangular components of a force of 100N is 50N. Find the other component.

3. 3Section I — (a) What is Friction? Discuss in detail about Static Friction, Kinetic Friction and Fluid Friction. (b) A helicopter is ascending at a rate of 12 m/sec. At a height of 80 m above the ground, a package is dropped. How long does the package take to reach the ground? (c) Write the differences between interference and Diffraction.

4. 4Section I — (a) What is Conservative force? How is it related to Potential energy? (b) What is the value of the gravitational acceleration at a distance of: (i) Earth's radius above the earth's surface (ii) Twice earth's radius above the earth's surface? (c) What is the difference between mass and weight? What are density and specific gravity?

5. 5Section I — (a) What is Simple Harmonic Motion? Define its condition and characteristics. (b) A standing wave is established in a 120 cm long string fixed at both ends. The string vibrates in four segments when driven at 120 Hz. (i) Determine the wave length. (ii) What is the fundamental frequency? (c) Write the difference between standing and progressive waves.

6. 6Section II — (a) What are the different theories of light? Briefly discuss and compare them. Which theory is considered most appropriate today? (b) Two convex lenses of equal focal length f are kept at a distance coaxially. A parallel beam of light incident on the first lens emerges from the 2nd lens as a parallel beam. Find the distance between the two lenses. (c) A concave mirror has a focal length of f cm. An object is placed such that it forms a two fold magnified real image. What is the distance between the object and the image?

7. 7Section II — (a) (i) Explain what is the difference between a resistance R and resistivity ρ? Give the relation between R and ρ. (ii) What length of copper wire whose area is 0.1 mm² and resistivity ρ = 1.7 × 10⁻⁸ Ωm is needed to provide a resistance of 3 Ω? (b) (i) Find the power consumed by a 240 Ω light bulb when the current through it is 0.5 A. (ii) A 200 Ω and a 500 Ω resistor are in series as part of a larger circuit. If the voltage across the 200 Ω resistor is 2 V, find the voltage across the 500 Ω resistor. (iii) A 20 Ω resistor, a 40 Ω resistor and a 50 Ω resistor are connected in parallel to a 60 V power source. Find the equivalent resistance of the set and the current in each resistor.

8. 8Section II — (a) What do you understand by radioactivity? Give an account of the properties of radiations emitted by radioactive substances. (b) What are Isotopes? Explain the isotopes of hydrogen. (c) What is Laser? Describe its principle.

9. 9Section II — Write notes on any 03 of the following: (a) Electric resistance and Ohm's Law (b) Electromagnetic waves (c) Ampere's Law (d) Nuclear fission and fusion (e) Transistor as an amplifier (f) Special theory of relativity