Phys 114 -final 2003

Pokhara University (B.Sc. Biochemsitry) 1st set Final Examination - 2003 Subject : Phys 114 Physics I Group: A Answer any three questions. Questions are of equal value.

F.M : 100 P.M : 50 Time: 3 hrs (3 X 14= 42)

1. Define angle of contact. Derive an expression for rise and fall of liquid in the capillary tube. 2. Explain solar system with detail explanation of Sun. 3. What is meant by hysteresis, residual magnetism, coercive force and permeability? Describe a method for obtaining hysteresis loop. 4. What are liquid crystals? What parameters describe the liquid crystalline structure? Describe phases of liquid crystal. Group: B Answer any six questions. Questions are of equal value. 6 X 7 = 42 1. Describe curvature of liquid surface of liquid. 2. The internal diameter of glass tube of a mercury barometer reads 74.45 cm Hg. Find the correct reading of barometer after allowing for the error due to surface tension. Density of mercury is 13600 kgm-3, surface tension = 3.5 × 10-1 Nm-1and its angle of contact = 1350. 3. During total solar eclipse, the disc of moon almost completely covers the disc of Sun. If the distance of sun from earth = 1.496 × 1011meter, diameter of Sun = 1.393 × 109m. Distance of moon from earth = 3.845 x108 m. Then calculate the diameter of moon. 4. Describe evolution of universe. 5. A constant voltage a.c. generator of 20V r.m.s and variable frequency is connected in series with a resistor of resistance 2.0 W, a coil of inductance 5.0 H and a capacitor of capacitance 2.0 mF. The frequency is adjusted until the current in the circuit has a maximum value of 2.0 A r.m.s. Calculate the resistance of the wire of the inductor and the value of this frequency. (Assume p2 =10). 7. Describe polarization of light. 8. Describe effects of electric and magnetic field on liquid crystal. Group: C Answer any eight questions. Questions are of equal value.

8 ´ 2 = 16

1. Why water spreads on the surface of glass but forms globules on the surface of leaf of certain plants? 2. Why ends of a glass rod become round when heated? 3. Reading of mercury barometer is always less then the actual pressure. Why? 4. Define solar constant. 5. Write about Asteroids. 6. What is black hole? 8. What are advantages of amplifier in electronic circuit? 9. Mesophase. 10. Polymorphism. 11. Nimetic Phases.

12. What do you mean by displacement current? Give the physical concept. Pokhara University (B.Sc. Biochemsitry) 2nd set Final Examination - 2003 Subject : Phys 114 Physics I Group: A Answer any three questions. Questions are of equal value.

F.M : 100 P.M : 50 Time: 3 hrs 3 ´ 14=42

1.

Define coefficient of surface tension. Show that the potential energy per unit area of liquid surface is equal to the coefficient of surface tension. 2. Explain about planets and their characteristics. Also describe about atmosphere of planets. 3. What is Freedericksz transition? Describe in detail what do you mean by the polarized light? How can you prove that polarized light is transverse waves? 4. What do you mean by "Electrical resonance"? Obtain an expression for the current in LCR-series circuit. What does mean the tuned in series circuit? Group: B Answer any six questions. Questions are of equal value. 6 ´ 7 = 42 1. Describe mechanism of emergence of surface tension. 2. Calculate the work done to break up a drop of mercury of diameter 1.0×10-2m into eight drops, all of the same size. Surface tension of mercury is 0.035 Nm-1. 3. Find the temperature of sun from following data. Distance between sun & earth = 1.496×1011m Solar constant = 1.388 ×103 w/m2 Radius of sun = 7×108 m Stefan's constant = 5.67 × 10-8 wm-2s-1k-1 4. Describe about death of stars. 5. Describe smectic and cholesteric phases of liquid crystal. 6. Describe differential scanning calorimetry . 7. Explain the operation of npn transistor as an amplifier in common emitter connection. How will you draw d.c. load line on the output characteristics of a transistor? What is its importance? 8. Describe a half wave rectifier using a crystal diode and obtain an expression for its efficiency of a half wave rectifier. Group: C Answer any eight questions. Questions are of equal value. 8 ´ 2 = 16 1. 2. 3. 4. 5. 6. 7. 8.

Why insects can walk on water surface? Why a body falling through a viscous liquid attains constant velocity? Water rises in a capillary tube but mercury is depressed. Why? Write about comets. Explain about sizes of stars. What is source of energy of sun? Nemetic Phase. What are the characteristics of liquid crystals?

9. Anisotropy. 10. What are the electromagnetic waves? 11. What are the advantages of oscillator in electrical circuit? 12. In the following circuit of a common base connection of a npn transistor, Ic = 0.95 mA and IB = 0.5 mA. Find the value of a.