I BNA-013 I B.Sc. (NAUTICAL SCIENCE) 00

Term-End Examination December, 2009

cO O

BNA-013 : ELECTRICITY AND ELECTRONICS Maximum Marks : 70

Time : 2 hours Note : (i)

Non-programmable scientific calculator is allowed. Attempt three questions from each section.

(iv)

Questions No. 1 and 5 are compulsory. In all you have to attempt Six questions. SECTION - A (Electricity)

1.

(a) With the help of a neat diagram explain the 10 principle, construction and working of an A. C. generator. (b) Two identical coils of 650 turns each lie in parallel planes such that 80% of magnetic flux produced by one coil links with the other. If a current of 3.5 amp in one coil produces a magnetic flux of 0.5 m wb in it, find the mutual inductance between the coils.

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1

5

P.T.O.



2.

3.

4.

(Attempt any two from the following three questions) : Define active, reactive and apparent power in an A.C. circuit. And also give the significance of power factor.

5

Two cells of emf 6V and 8V having internal resistance of IQ and 211 respectively are connected in parallel. External resistance of 411 is connected across the combination. Find the terminal voltage of each cell.

5

(a) How do you convert a given galvanometer into a voltmeter ? Explain with necessary circuit diagram.

5

(b) A galvanometer of resistance 20011 has 100 divisions. When a 'potential difference of 15 mV is applied to its terminal, it deflects by 5 divisions. How can it be converted into an ammeter to read 10 amp ?

5

Write short notes on

any two

of the following : 5+5

Transformer Variation of resistance with temp (c) Kirchoff s laws

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SECTION - B (Electronics) (a) Explain CB amplifier using NPN transistor 10 with necessary circuit diagram. (b) The input resistance of a common - emitter amplifier is 2 kIl and current gain is 120. If the load resistance used is 5kfl. Calculate output voltage for an input voltage of 5 mV.

5

(Attempt any two from the following three questions) : What is demodulation ? Explain FM detector with simple circuit diagram.

5

A sinusoidal carrier voltage of frequency 1250 KHz is amplitude modulated by a sinusoidal voltage of frequency 12 KHz resulting in maximum and minimum modulated carrier amplitude of 60V and 40V respectively.

5

Calculate : (1)

Frequency of lower and upper side bands. Unmodulated carrier amplitude. Modulation index and Amplitude of each side band.

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3

P.T.O.



7.

8.

(a) Explain the working of a radio transmitter with necessary block diagram.

5

(b) A piezo - electric crystal has the following parameters : L = 0.12 H, C = 20 pF, Cm = 360 pF and R = 7.2 kIl. Find series and parallel resonant frequencies.

5

Write short notes on any two of the following : 5+5 Light Dependent Resistor Pressure transducer (c) RADAR -o0o-

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