JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II ELEMENTS OF ELECTRICAL AND ELECTRONICS ENGINEERING Previous Question Paper (November/December - 2018 - R13)
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. Each question carries 10 marks and may have a, b, c as sub questions.
Part A
Define Ohm’s Laws.
Answer
Ohm's Law states that the current flowing through a conductor between two points is directly proportional to the voltage across the two points, provided the temperature and other physical conditions remain constant. Mathematically, V = IR, where V is voltage in volts, I is current in amperes, and R is resistance in ohms.
Derive torque equation of DC motor.
Answer
The mechanical power developed in a DC motor is P = EbIa. Since P = Tω, where T is torque and ω is angular velocity, we have T = (EbIa) / ω. Substituting Eb = (PΦZN) / (60A) and ω = (2πN) / 60, the torque equation becomes T = (PΦZIa) / (2πA), which simplifies to T = kΦIa, where k is a constant depending on machine design.
Write principle of operation of transformer.
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Why three phase induction motor is not running at synchronous speed.
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Write different types of indicating instruments.
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List the advantages & disadvantages of MI type instruments.
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What is a transistor? What are the types?
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Draw V-I characteristics of diode.
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Write applications of CRO.
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Explain Sensitivity of CRO.
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Part B
Find the current I supplied by the battery of the Figure through delta/star transformation.
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The armature of a 2-pole, 220 V Lap wound generator has 400 conductors and runs at 300 rpm. Calculate the useful flux/pole, if the number of turns in each field coil is 1200.
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Explain principle of operation of DC Generator.
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Why starter is required to start DC motor and explain three point starter.
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Derive EMF equation of single phase transformer.
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Explain synchronous impedance method for regulation of alternator.
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Explain Principle of operation of alternators.
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Explain slip-Torque characteristics of three-phase induction motor.
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Explain the principle, construction and working of PMMC type instrument and derive the expression for the deflecting torque.
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Define measurements and what are basic requirements for the indicating instruments explain in detail.
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Explain construction and working principle of MI instruments and write applications of MI instruments.
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Discuss PN diode VI characteristics.
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With neat diagrams, explain SCR with its characteristics.
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Derive the ripple factor expression for FWR with inductor filter.
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Explain the construction and working function of NPN transistor in detail.
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Explain Electrostatic focusing system of a CRT.
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Explain Refraction of an electron ray at an equipotential surface.
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Describe how the following measurements can be made with the use of CRO. i) Phase Angle ii) Frequency.
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Why are operating voltages of CRT arranged so that the defection plates are nearly at Ground potential.
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