Rajasthan Technical University 2009-1st Year B.E Tele Communication Engineering (Annual) (Back) , y- - Question Paper
(a) If a sinusoidal e.m.f. e = Esin cot is applied across a series "" RL circuit, what is the equation for current ? Derive, also
power consumed in such a circuit.
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(b) A resistor R in series with a capacitor C is connected to a 50 Hz, 240 V supply. Find thfr value of C so that R absorbs 300 W at 100 V.
L
Fig. S OR
Derive with neat circuit and phasor diagrajna, the relationship between the phase and line voltages and currents for a balanced three phase delta connected load, and hence deduce an expression for the total three phase pcrfrer in terms of the line voltage, the line current and the power factor.
f two Wattmeter method for
(b) How power canbQ
/-/ Hwtori8Blofer?iE>g#ive an expression
. (W|-Wt) (W,+Wj)
/ (a) What is working principle of 1-+ transformer ? Derive the / EMF equation for 1-$ transformer.
8
(b) A 250 kVA, 11000/415 V, 50 Hz single phase transformer has 80 turns on the secondary.
Calculate :
(i) The approximate values of the full load primary and secondary currents.
(ii) The approximate number of primary turns.
(iii) The max. value of the flux.
8
OR
(a) If a sinusoidal e.m.f. e = Esin cot is applied across a series "" RL circuit, what is the equation for current ? Derive, also
power consumed in such a circuit.
8
(b) A resistor R in series with a capacitor C is connected to a 50 Hz, 240 V supply. Find thfr value of C so that R absorbs 300 W at 100 V.
L
Fig. S OR
Derive with neat circuit and phasor diagrajna, the relationship between the phase and line voltages and currents for a balanced three phase delta connected load, and hence deduce an expression for the total three phase pcrfrer in terms of the line voltage, the line current and the power factor.
f two Wattmeter method for
(b) How power canbQ
/-/ Hwtori8Blofer?iE>g#ive an expression
. (W|-Wt) (W,+Wj)
/ (a) What is working principle of 1-+ transformer ? Derive the / EMF equation for 1-$ transformer.
8
(b) A 250 kVA, 11000/415 V, 50 Hz single phase transformer has 80 turns on the secondary.
Calculate :
(i) The approximate values of the full load primary and secondary currents.
(ii) The approximate number of primary turns.
(iii) The max. value of the flux.
8
OR
Explain different types of torques presents in indicating type of measuring instruments.
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(b) Explain the construction and working principle of /electrodynamometer type instruments.
8
4 (a) Draw the V-I characteristics of a junction diode and explain
the cut in voltage and peak inverse
(b) Explain with a neat circuit diagram, the working of a bridge rectifier and deduce expression for its ripple factor and efficiency. What are the advantages of this rectifier over the full wave rectifier using two diodes ?
8
/' (a) Describe zener breakdown mechanism. How is it difficult trom avalanche breakdown ? Draw a zener diode voltage requlator circuit to regulate the voltage across a load resistance. Explain its working.
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Explain drffepfc type? flf, filters used in electronic circuits.
5 Wf For CE configuration, prove that Ic~Pibt'HP+1)ic0 In v./ common base configuration the emitter current is 1.6 mA.
The collector current with emither circuit open is 10 nA. Determine the total collector current.
8
(bj/'What are the three configurations of transistor amplifier ? Compare them with regard to their input impedance, output impendance, current and voltage gain.
5 (a) Explain with the help of a suitable diagram, the principle of operation of an oscillation. State and explain the criteria _ for sustained oscillations.
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[ 3000 ]
(J>) Explain the function of modulation and demodulation in a
< communication system.
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| Earning: Approval pending. |
