JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II ELEMENTS OF ELECTRICAL AND ELECTRONICS ENGINEERING Previous Question Paper (April/May - 2018 - R15)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit.
Part A
Define back EMF of d.c. motor.
Answer
The back EMF (electromotive force) is the voltage induced in the armature conductors of a d.c. motor as they rotate in the magnetic field, which opposes the applied voltage according to Lenz's law.
Define KVL with an example.
Answer
Kirchhoff's Voltage Law (KVL) states that the algebraic sum of all voltages around any closed loop in a circuit is zero. For example, in a simple series circuit with a voltage source V and two resistors R1 and R2, the law is expressed as V - IR1 - IR2 = 0.
What are the Iron losses in 1-Ļ transformer?
Answer
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What is the value of torque of induction motor at zero slip? Why?
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Define damping torque in an indicating instrument.
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What are the limitations of PMMC instruments?
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Define reverse bias in PN Junction diode.
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What is the relationship between base collector and emitter currents in a transistor?
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What are the full forms of CRT and CRO?
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What is lissajous pattern?
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Part B
Explain the principle of operation of DC generator.
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In the circuit shown in figure 1, determine i1 and i2.
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Explain in detail about the working of three point starter.
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Find the voltage āVā in the circuit shown in figure 2.
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Explain the working principle of induction motor.
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The No load current of a transformer is 1 A and 0.3 power factor when supplied at 230-V, 50-Hz. The number of turns on the primary winding is 100. Calculate (i) the maximum value of flux in the core (ii) the core loss (iii) the magnetizing current.
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Discuss in detail about the synchronous impedance method used to find voltage regulation of an alternator.
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A single phase transformer has 200 primary and 800 secondary turns. The net cross sectional area of the core is 50 cm2. If the primary winding be connected to a 50-Hz supply at 220 V, calculate the peak value of flux density in the core and the voltage induced in the secondary winding.
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Explain the basic construction of PMMC instruments.
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Explain the principle of operation of moving iron instruments.
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Discuss in detail about the advantages of moving iron instruments.
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Explain the advantages of PMMC instruments.
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With the help of neat sketch, explain about full wave bridge rectifier.
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Explain the SCR characteristics with neat diagram.
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Draw the structure of a PNP transistor and explain its CB configuration characteristics.
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Discuss the constructional details of a PN junction diode.
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Explain various parts of CRT.
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How frequency is measured using CRO? Explain with an example.
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Explain in detail about magnetic deflection in CRO.
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How current is measured using CRO? Explain with an example.
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