JNTU
JNTU B.Tech II ELECTRICAL ENGINEERING Previous Question Paper (September/October - 2023 - R16)
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 Lenz’s law.
Answer
Lenz's law states that the direction of an induced electromotive force (EMF) and the resulting induced current in a closed circuit is always such that it opposes the change in magnetic flux that produced it. This law is a direct consequence of the Law of Conservation of Energy, ensuring that energy is not created from nothing.
Elucidate ideal voltage and current source.
Answer
An ideal voltage source is a two-terminal circuit element that maintains a constant terminal voltage regardless of the current flowing through it. Its internal resistance is zero, meaning the voltage remains fixed at its specified value for any load connected to it.
An ideal current source is a two-terminal circuit element that delivers a constant current to any load connected across its terminals, independent of the voltage across it. Its internal resistance is considered infinite, ensuring that the current remains constant regardless of the external circuit impedance.
What is the meaning of three phase balanced circuits?
Answer
Sign in to view the complete answer paper.
Draw the power triangle of an ac circuits.
Answer
Sign in to view the complete answer paper.
What are the losses in DC motor?
Answer
Sign in to view the complete answer paper.
Describe the significance of back emf in a DC motor.
Answer
Sign in to view the complete answer paper.
Write the difference between ideal and practical transformers.
Answer
Sign in to view the complete answer paper.
Define Slip and Slip speed.
Answer
Sign in to view the complete answer paper.
What are the differences between d.c. generator and an alternator?
Answer
Sign in to view the complete answer paper.
Why the open circuit test is conducted in synchronous generator?
Answer
Sign in to view the complete answer paper.
Part B
State and explain faradays laws of electromagnetic induction.
Answer
Sign in to view the complete answer paper.
Find the equivalent resistance between points A & B in the network shown.
Answer
Sign in to view the complete answer paper.
Discuss the construction and principle operation of moving coil instruments.
Answer
Sign in to view the complete answer paper.
Explain the force on a current carrying conductor in magnetic field.
Answer
Sign in to view the complete answer paper.
Explain the generation of an alternating EMF with neat diagrams.
Answer
Sign in to view the complete answer paper.
Find the voltage across R, L, phase angle in series R-L circuit, with R = 100 ohms and L = 100mH and input voltage 10V, 100Hz. Also draw the phasor diagram.
Answer
Sign in to view the complete answer paper.
Derive the average and rms values of sinusoidal waveform.
Answer
Sign in to view the complete answer paper.
The voltage and current in a circuit with 50Hz supply are represented as V(t) = 280 Sin ωt and i(t) = 14.14 Sin (ωt – π/6). Find i) RMS value of current ii) Average value of voltage iii) Power consumed in the circuit iv) Draw the phasor diagram of current and voltage.
Answer
Sign in to view the complete answer paper.
Derive emf equation of dc generators.
Answer
Sign in to view the complete answer paper.
Calculate the emf generated by 4 pole wave wound generator having 65 slots with 12 conductors per slot when driven at 1200 rpm. The flux per pole is 0.02 wb.
Answer
Sign in to view the complete answer paper.
Explain the principle of working of a DC Motor.
Answer
Sign in to view the complete answer paper.
Explain the procedure for conducting the Swinburne’s test on DC motor with neat sketch.
Answer
Sign in to view the complete answer paper.
Explain the working of a single-phase transformer.
Answer
Sign in to view the complete answer paper.
In 50KVA single phase transformer the iron loss is 500W and full load copper loss is 800W. Determine its efficiency at full load at 0.8 p.f. lag.
Answer
Sign in to view the complete answer paper.
Draw and discuss the torque – slip characteristics of 3-phase induction motor.
Answer
Sign in to view the complete answer paper.
A Three-phase induction motor is wound for four poles and supplied from a 50-Hz supply. Calculate i) the Synchronous speed, ii) the speed of the rotor when the slip is 3% and the rotor frequency when the speed of the rotor is 900rpm.
Answer
Sign in to view the complete answer paper.
Explain the constructional aspect of the Synchronous generator. Also, explain its working.
Answer
Sign in to view the complete answer paper.
Explain in detail about the method of calculation of voltage regulation of an alternator by synchronous impedance method.
Answer
Sign in to view the complete answer paper.