JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II Year ELEMENTS OF ELECTRICAL AND ELECTRONICS ENGINEERING Previous Question Paper (September/October - 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
State Ohm’s Law.
Answer
Ohm's Law states that the current flowing through a conductor is directly proportional to the potential difference across its ends, provided the temperature and other physical conditions remain constant.
What is the need of starter for DC motors?
Answer
A starter is required for DC motors because at the moment of starting, the back EMF is zero. Since the armature resistance is very low, the motor would draw an excessively high current, which could damage the armature windings. The starter introduces external resistance to limit this starting current to a safe value until the motor gains speed.
What are the functions of a transformer?
Answer
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What are the merits and demerits of induction motor?
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What is mean by secondary instruments? Classify them.
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What are the errors in moving iron instruments with both DC and AC?
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What is an ideal diode? Draw its characteristics?
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Discuss the operation of an SCR.
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What is electrostatic deflection of CRT?
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Explain magnetic deflection of CRT.
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Part B
State and explain Kirchoff’s Laws.
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In the circuit shown in figure, find the value of current flowing through all resistances.
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Derive the torque equation for a DC motor.
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A certain wave wound DC generator running at a speed of 300rpm is to generate an induced emf of about 535V, the flux per pole being 0.055wb. Determine the number of poles, if the number of conductors is 650.
Answer
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Explain the principle of operation of single phase 2- winding transformer.
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A single phase 50 Hz transformer has a core cross – sectional area of 100 cm2, and the maximum flux density of 1.25 Wb/m2. There are 1200 turns in primary and 100 turns in the secondary windings. Calculate the induced e.m.fs on both sides.
Answer
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Describe how you can determine the regulation of a synchronous generator from open circuit and short circuit tests.
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A four pole, three phase induction motor when supplied with 400 V, 50 Hz supply rotates at a slip of 4 %. What is the speed of the motor?
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Explain why a moving iron instrument is called either an attraction type or repulsion type. Describe the principle of working of one of them.
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Describe the working of moving coil instrument. Discuss why it is suitable on DC only.
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Explain how a p-n junction can be used to work as a diode.
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Draw and explain a single phase half wave controlled rectifier.
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Describe the construction and working principle of a bipolar junction transistor.
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Explain with the help of a circuit the working of a transistor as an amplifier.
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Draw the block diagram of CRO and explain the operation of each block.
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Discuss the applications of CRO.
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