BT-104 (GS) – Basic Electrical and Electronics Engineering

B.Tech. I & II Semester
Examination, November 2022
Grading System (GS)
Max Marks: 70 | Time: 3 Hours

Note:
i) Attempt any five questions.
ii) All questions carry equal marks.

Previous Year Questions (November 2022)

Q.1

a) Find the voltage $V_{ab}$ in the network shown below. (Unit 1)

Circuit diagram for Q.1(a). The left side has a 2A current source in parallel with two 5-ohm resistors (one above, one below). A 10-ohm resistor connects the junction of the 5-ohm resistors to node 'a'. The right side has a 6-ohm resistor and a 4-ohm resistor in series, with a 30V source connected across them. Node 'a' is the junction between the 10, 6, and 4-ohm resistors. Node 'b' is the other terminal of the 4-ohm resistor. The objective is to find the voltage Vab across the 4-ohm resistor.

b) Find the current through the $6 \Omega$ resistor using Thevenin's theorem. (Unit 1)

Circuit diagram for Q.1(b) showing three parallel branches. The first branch has an 18V DC source in series with a 1-ohm resistor, and the voltage across this resistor is labeled Vx. The second branch contains a 3A current source pointing upwards. The third branch contains a dependent voltage source of 2Vx in series with a 6-ohm resistor. The task is to find the current flowing through the 6-ohm resistor using Thevenin's theorem.
Q.2

a) Draw Phasor diagrams of the following circuits. (Unit 2)

i) Series R-L-C when $X_L > X_C$

ii) Series R-L-C when $X_L < X_C$

iii) Series R-L-C when $X_L = X_C$

b) A 3-$\phi$ balanced system supplies 110V to a delta connected load whose phase impedance is equal to $(3.54+j3.54)\Omega$. Determine the line currents and draw the Phasor diagram. (Unit 2)
Q.3

a) Draw Phasor diagram of a 3-phase delta connected load and find the relation between phase and line voltages and currents. (Unit 2)

b) A 220 V, 100 Hz, A.C source supplies a series RLC circuit with a capacitor and a coil. If the coil has 50 mH inductance, find at a resonance frequency of 100 Hz, what is the value of capacitor? (Unit 2)
Q.4

a) Draw the typical normal magnetization curve of ferromagnetic material. (Unit 3)

b) Explain in detail the Applications of DC Machines. (Unit 4)
Q.5

a) Draw and explain the output characteristic of a NPN transistor operation in CE configuration. (Unit 5)

b) The no-load ratio required in a single-phase 50 Hz transformer is 6600/600 V. If the maximum value of flux in the core is to be about 0.08 Wb, find the number of turns in each winding. (Unit 3)
Q.6

a) Enumerate the various losses in a transformer. How these losses can be minimized? (Unit 3)

b) Explain the construction and working principle of three-phase induction motor with suitable diagram. (Unit 4)
Q.7

a) What is the difference between a separately excited and a self-excited generator? (Unit 4)

b) An 8-pole DC machine has a wave winding containing 600 conductors. Calculate the generated e.m.f when the flux per pole is 0.08 Wb and speed is 215 rpm. If the flux per pole is made 0.05 Wb. At what speed should the armature be driven to generate 5001V. (Unit 4)
Q.8

Write short notes on: (any two)

a) R-S flip-flop (Unit 5)

b) J-K flip-flop (Unit 5)

c) De-Morgan's theorem (Unit 5)

d) Star Delta transformation (Unit 1)