Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech II ELECTRICAL AND ELECTRONICS ENGINEERING Previous Question Paper (April/May - 2023 - R15)
Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions. iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
Part A
Define Ohms law and state if there are any conditions.
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 and inversely proportional to the resistance between them, provided all physical conditions and temperature remain constant.
The primary condition for Ohm's law is that the temperature and other physical properties of the conductor must remain constant. It is only applicable to ohmic conductors and does not apply to non-linear devices like diodes, transistors, or electrolytes.
Give the effective resistance when three resistances are connected in parallel.
Answer
When three resistances R1, R2, and R3 are connected in parallel, the reciprocal of the effective or equivalent resistance (Req) is equal to the sum of the reciprocals of the individual resistances. The formula is given by:
Solving for Req, the effective resistance is:
What is the purpose of yoke in a DC machine?
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What is the basic principle of a DC generator?
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What is meant by a transformer?
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What do you mean by pole pitch and coil pitch? What is the relationship between mechanical degrees and electrical degrees?
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What is PN junction?
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Compare the three transistor configuration with regard to input and output resistance, current and voltage gain.
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What is mean by sensitivity of a CRT?
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What are the applications of CRO?
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Part B
State the factors on which resistance of a wire depends. What is meant by resistivity of a conducting material?
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In the circuit shown in figure, determine the resistance between the terminals x and y.
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What do you mean by PMMC instruments.
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Explain the working of moving coil instrument. List out its merits and demerits.
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Why is the air-gap made as small as possible between the armature and the poles in a DC machine.
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Derive the equation for induced EMF in a DC generator.
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Explain the working of three point starter in DC motors with neat diagram.
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A 250V, DC shunt motor takes a line current of 20A, resistance of shunt field winding is 200 ohms and resistance of the armature is 0.3 ohms. Find the armature current and the back emf.
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From the fundamentals, derive the expression for the EMF equation of a single phase transformer.
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Develop the equivalent circuit of a single phase transformer.
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Explain the principle of operation of alternators.
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A 3-phase, 6-pole induction motor is connected to a 60 Hz supply. The voltage induced in the rotor bars is 4 V when the rotor is at standstill. Calculate the voltage and frequency induced in the rotor bars at 300 r.p.m.
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Discuss the working of a PN junction diode with diagrams. Also explain its V-I characteristics.
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Draw and explain the operation of full wave bridge rectifier with neat diagrams.
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Explain the working of the CB configuration of a BJT.
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Discuss the output and input characteristics of a transistor in CC configuration.
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Describe the working of Cathode Ray Oscilloscope with a neat sketch.
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Obtain the expression for electrostatic deflection sensitivity of CRT.
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Discuss frequency measurement with CRO.
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