JNTU
JNTU B.Tech II ELEMENTS OF ELECTRICAL AND ELECTRONICS ENGINEERING Previous Question Paper (March - 2021 - R15)
Answer any five questions
All questions carry equal marks
Main
State and explain Kirchhoff’s Laws with necessary example of each.
Answer
Kirchhoff's Current Law (KCL) states that the algebraic sum of currents meeting at a node (or junction) in an electrical circuit is zero. Mathematically, ΣI = 0. This is based on the principle of conservation of charge. For example, if currents I1 and I2 enter a node and I3 leaves it, then I1 + I2 = I3.
Kirchhoff's Voltage Law (KVL) states that the algebraic sum of all voltages around any closed loop in a circuit is zero. Mathematically, ΣV = 0. This is based on the principle of conservation of energy. For example, in a loop with a voltage source V and two resistors R1 and R2 in series, V - IR1 - IR2 = 0, meaning the source voltage equals the sum of the voltage drops across the resistors.
A 50Ω resistor is in parallel with a 100Ω resistor. The current in 50Ω resistor is 7.2A. What is the value of third resistance to be added in parallel to make the total current 20.1A?
Answer
First, determine the voltage across the parallel circuit. Since the 50Ω and 100Ω resistors are in parallel, the voltage V across them is the same:
The current through the 100Ω resistor is:
The total current is 20.1 A. The current through the third resistor (R_3) is the total current minus the sum of the first two currents:
Since R_3 is in parallel, the voltage across it is also 360 V. Therefore:
Explain the following with respect to DC Machine: i) Field System ii) Armature core & Winding iii) Commutator iv) Brushes.
Answer
Sign in to view the complete answer paper.
Explain the operation of a three point starter with a neat diagram.
Answer
Sign in to view the complete answer paper.
List and explain the various losses that are considered in a single phase transformer.
Answer
Sign in to view the complete answer paper.
A single phase transformer on no –load takes 5 A at a power factor of 0.6 lagging when connected to 230V, 50 Hz supply. The number of turns of the primary winding is 230. Calculate i) the magnetizing current ii) the core loss and iii) the maximum value of flux in the core.
Answer
Sign in to view the complete answer paper.
Explain how rotating magnetic field is created in three phase Induction motor.
Answer
Sign in to view the complete answer paper.
Explain about the following Electrical instruments with an example of each type: i) Indicating Instrument ii) Integrating Instrument iii) Recording Instrument.
Answer
Sign in to view the complete answer paper.
Explain the working of Attraction type of Moving iron Instrument with a neat diagram.
Answer
Sign in to view the complete answer paper.
Explain different torques required for the operation of indicating instruments.
Answer
Sign in to view the complete answer paper.
Explain the working of a half wave rectifier with a neat circuit and necessary waveforms.
Answer
Sign in to view the complete answer paper.
A half wave diode rectifier is transformer fed from a 230 V supply. Calculate: i) turn ratio and ii) diode PIV rating if the circuit provides an output of 12V dc.
Answer
Sign in to view the complete answer paper.
Explain the different parts of a Cathode ray tube with a neat diagram.
Answer
Sign in to view the complete answer paper.
Explain how phase and frequency measurements can be done using the cathode ray oscilloscope.
Answer
Sign in to view the complete answer paper.