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

B.Tech. I/II Semester
Examination, December 2025
Grading System (GS)
Max Marks: 70 | Time: 3 Hours

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

Previous Year Questions (December 2025)

Q.1

a) State the steps to solve the Thevenin's Theorem. An Electric iron is rated 1000W, 240V. Find the current drawn & resistance of the heating element. (Unit 1)

b) Find the current through 3 Ω resistor using superposition theorem in given figure. (Unit 1)

A circuit diagram consisting of two adjacent rectangular loops sharing a common middle vertical branch. The left vertical branch has a 20V DC voltage source with the positive terminal at the top. The top horizontal branch of the left loop contains a 5 Ω resistor. The shared middle vertical branch contains a 3 Ω resistor. The right vertical branch contains a 40V DC voltage source with the positive terminal at the bottom and negative terminal at the top. The bottom horizontal branch of the right loop contains a 6 Ω resistor. The top branch of the right loop and bottom branch of the left loop are plain wires.
Q.2

a) Explain about Star and Delta connected three phase balanced circuits. (Unit 2)

b) A series RLC circuit containing a resistance of 12Ω, an inductance of 0.15H and a capacitor of 100μF are connected in series across a 100V, 50Hz supply. Calculate the total circuit impedance, the circuits' current, power factor and draw the voltage phasor diagram. (Unit 2)
Q.3

a) Derive expression for the coefficient of:
(i) Self-inductance for a solenoid coil
(ii) Mutual inductance for a pair of closely wound solenoid coils (Unit 3)

b) Discuss some of the magnetization characteristics of ferromagnetic materials. (Unit 3)
Q.4

a) With a neat circuit diagram and explain the construction and principle of operation of DC Motor. (Unit 4)

b) A three phase 50Hz, 2 pole induction motor has a full speed of 2860 rpm. What is the (i) synchronous speed (ii) slip of the induction motor (iii) rotor emf frequency? (Unit 4)
Q.5

a) Define α and β with respect to BJT and derive the relationship between them. For a transistor circuit having α = 0.98, $I_{CBO}$ = 5 μA and $I_B$ = 100 μA, find $I_C$ and $I_E$. (Unit 5)

b) When three balanced impedances are connected in delta across a 3 phase 400 V, 50 Hz supply the line current drawn is 20 A at a lagging p.f. of 0.3. Determine the value of the impedance connected in each phase. (Unit 2)
Q.6

a) Determine the equivalent resistance between terminals A and B in the given figure. (Unit 1)

A bridge circuit diagram with input terminal A on the left and output terminal B on the right. The circuit splits at A to a top node and a bottom node. A 6 Ω resistor connects A to the top node, and a 20 Ω resistor connects A to the bottom node. A 10 Ω resistor vertically connects the top node and the bottom node. From the top node, a 4 Ω resistor connects to terminal B. From the bottom node, a 15 Ω resistor connects to terminal B.

b) Draw the circuit of an S-R flip flop using NAND gates. Explain it. (Unit 5)
Q.7

a) State and Prove Demorgan's theorem. (Unit 5)

b) Explain about open circuit and short circuit test. (Unit 3)
Q.8

Write technical short note on any two of the following:

(i) Voltage and current sources (Unit 1)

(ii) Applications of DC machine (Unit 4)

(iii) Half and Full adder circuits (Unit 5)