Madras University (UnOM) 2005 B.Sc Electronics ELECTRICITY AND BASIC - Question Paper

ELECTRICITY AND BASIC ELECTRONICS

NOVEMBER 2005 PJ1A
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Time :Three hours Maximum : 100 marks


PART A-(10x3=30 marks)

ans any Ten ques..

All ques. carry equal marks.


1. A certain charge Q is divided into 2 parts q and Q–q. How the charges Q and q must be related so that when experience maximum electrostatic repulsion.

2. obtain out the pints where (a) V=0 and (b) E=0 in the subsequent figure:
p +q -3q

r 1m
3. What is the energy of the charged conductor (a) interms of charge and capacitance (b) potential and capacitance and (c) charge and potential ?

4. obtain the capacitance of the system of 3 parallel plates every of area Am2 , separated by d1 and d2 metres. The space ranging from them is filled with dielectricsof relative dielectric constants ?1 and ?2 (The dielectric of free space is ?0 )

A ?1 ?2

d1 d2
5.Show that for maximum current, the cells should be connected in mixed grouping with external resistance is equal to the net internal resistance .

6. What is the principle of potentiometer?

7. Draw circuit diagram of bridge rectifier and elaborate its advantages and disadvantages.

8. What is the purpose of clipper and clamper? How clipping at 2 various levels can be made?

9. Compare the performance of common-emitter, common collector and common base transistor amplifiers.

10.State Thevenins theorem and prove it in case of 2 terminal network.

11. Draw the symbols for (a) AND gate (b) OR gate and (c)NOT gate . provide its truth table.

12. A current of one A is flowing in the sides of an equilateral triangle of side 4.5x10-2 m. obtain the magnetic field at the centroid of the triangle.


PART B-(5x6=30 marks)

ans any 5 ques..

All ques. carry equal marks.
13. Derive a relation for the potential at any point P due to an uniformly charged disc.

14. define the quadrant electrometer. How ionization current can be measured with it.

15. Derive a relation for torque on a current loop in a uniform magnetic field.

16. Compare the L-section or inductor input filter with that of the p-section or capacitor input filter.

17. discuss the response of high pass RC circuit to (a) sinusoidal input (b) square wave input and (c) exponential input.

18. Using the method of electrical images, determine the surface density of induced or polarized charge on a dielectric slab of infinite face in front of a point charge.

19. compute the voltage gain of a CE amplifier from the subsequent data :
hf =100, RL =15K?, hi=60 K?, and ?h=12.

PART C-(4x10=40 marks)

ans any 4 ques..

All ques. carry equal marks.

20. Derive a relation for the electrostatic energy of a charged sphere.

21. Show that there is always a loss of energy on charges ranging from 2 condensers.

22. define with necessary theory the method of measuring the low resistance using a Carey Foster’s bridge.

23. define a P-N junction full wave rectifier. Derive relation for its efficiency. What is its ripple factor?

24. find expressions for the current gain, voltage gain, input impedance and output impedance and output impedance in terms of hybrid parameters for Ce amplifier.

25. The mid frequency gain of an RC coupled amplifier is 200. The value of the lower and upper cut-off frequencies are fL =50Hz and fH =100kHz.Find the frequencies at which the gain is decreased to 150.

Earning:   Approval pending.