Question 1

**PART - A**

Accepted Answer

Active elements can independently generate and deliver electrical energy continuously, whereas passive elements can only consume, dissipate, or temporarily store electrical energy within a circuit.

Question 2

Q.2 State Thevenin's theorem.

Accepted Answer

Thevenin's theorem mathematically simplifies any complex linear bilateral network into a single equivalent voltage source in series with a single equivalent resistance across two terminals.

Question 3

Q.3 Define root mean square (RMS) value.

Accepted Answer

The Root Mean Square (RMS) value constitutes the precise effective value of an alternating current that produces the exact identical thermal heating effect as an equivalent direct current.

Question 4

Q.4 What is power factor?

Accepted Answer

Power factor is precisely the mathematical cosine of the phase angle difference between voltage and current, representing the exact ratio of real active power to apparent power.

Question 5

Q.5 Mention the types of DC motors.

Accepted Answer

DC motors are systematically classified based strictly on how the stationary field windings are electrically connected relative to the rotating armature: Shunt, Series, and Compound motors.

Question 6

Q.6 What is the purpose of transformer?

Accepted Answer

A transformer is a static electromagnetic device engineered to rigorously step up or step down alternating voltage levels while strictly maintaining absolutely constant frequency.

Question 7

Q.7 Define slip in induction motor.

Accepted Answer

Slip is algebraically defined as the fractional relative difference between the synchronous speed of the stator's rotating magnetic field and the actual physical speed of the rotor.

Question 8

Q.8 List the components of power system.

Accepted Answer

A modern electrical power system is systematically composed of three primary interconnected functional stages: Power Generation, High-Voltage Transmission, and Low-Voltage Distribution networks.

Question 9

Q.9 Mention two protective devices in household wiring.

Accepted Answer

Two universally utilized protective electrical devices in domestic installations are safety Fuses and Miniature Circuit Breakers (MCB), both explicitly designed to strictly interrupt dangerous fault currents.

Question 10

Q.10 What is ELCB?

Accepted Answer

An Earth Leakage Circuit Breaker (ELCB) is a critical specialized safety instrument engineered strictly to detect hazardous stray leakage currents to earth and proactively disconnect the electrical supply.

Question 11

**PART - B**

Accepted Answer

Kirchhoff's Circuit Laws formally comprise Kirchhoff's Current Law (KCL), based entirely on the strict conservation of electric charge, and Kirchhoff's Voltage Law (KVL), based strictly on the fundamental conservation of electrical energy. Together, they provide the absolute foundation for comprehensively analyzing complex electrical networks.

Question 12

Q.2 Derive expression for RMS and average value of sinusoidal wave.

Accepted Answer

For a standard pure sinusoidal alternating current wave expressed precisely as $v(t) = V_m \sin(\omega t)$, the rigorously derived mathematical Root Mean Square (RMS) value is $V_{rms} = \frac{V_m}{\sqrt{2}}$, and the absolute average value over a strict half-cycle is exactly $V_{avg} = \frac{2V_m}{\pi}$.

Question 13

Q.3 Explain the working of single phase transformer.

Accepted Answer

A transformer systematically functions strictly on Faraday's fundamental Law of Mutual Electromagnetic Induction, seamlessly transferring alternating electrical energy entirely between isolated circuits via a continuously alternating physical magnetic flux confined within a high-permeability core.

Question 14

Q.4 Explain the speed-torque characteristics of DC series motor.

Accepted Answer

A DC series motor intrinsically exhibits an exceptionally high starting torque characteristic, but its rotational speed is dangerously inversely proportional to the applied mechanical load, strictly forbidding unloaded starting operations.

Question 15

Q.5 Differentiate between star and delta connection in 3-phase systems.

Accepted Answer

In a three-phase system, a Star (Y) connection features a line voltage mathematically equal to $\sqrt{3}$ times the phase voltage with identical line and phase currents, whereas a Delta ($\Delta$) connection features a line current equal to $\sqrt{3}$ times the phase current with identical line and phase voltages.

Question 16

Q.6 Explain the working of synchronous generator.

Accepted Answer

A synchronous generator rigorously operates on Faraday's law of electromagnetic induction, systematically converting mechanical prime-mover rotational energy entirely into three-phase alternating electrical power via a rotating direct-current magnetic field cutting stationary stator conductors.

Question 17

Q.7 Discuss different types of wires and cables used in internal wiring.

Accepted Answer

Electrical wires are universally classified by their distinct insulating materials, such as VIR, CTS, and the ubiquitous PVC, while heavy electrical cables are strictly categorized as either armoured for extreme physical protection or unarmoured for standard enclosed routing.

Question 18

**PART - C**

Accepted Answer

Nodal analysis is a highly systematic mathematical methodology for determining the exact voltage at every geometric node within an electrical circuit by rigorously applying Kirchhoff's Current Law (KCL) and Ohm's Law.

Question 19

Q.2 Analyze a series R-L-C circuit and derive the expression for resonant fre…

Accepted Answer

Resonance strictly occurs in an AC circuit when the inductive reactance exactly mathematically equals and structurally cancels the capacitive reactance ($X_L = X_C$), resulting in a completely pure resistive impedance and perfectly maximizing current flow at a highly specific resonant frequency.

Question 20

Q.3 Describe the working and construction of a DC machine.

Accepted Answer

A DC machine fundamentally consists of a stationary magnetic stator and a rotating commutated armature, systematically functioning as either a generator (converting mechanical power to DC electrical power) or a motor (converting DC electrical power to mechanical torque).

Question 21

Q.4 Explain the working of a 3-phase induction motor with a neat sketch.

Accepted Answer

A 3-phase induction motor functions rigorously on the principle of electromagnetic induction, where a completely mathematically balanced three-phase stator supply systematically creates a constant-amplitude rotating magnetic field (RMF) that dynamically cuts short-circuited rotor conductors, inducing a continuous driving torque.

Question 22

Q.5 Write short notes on: (a) Battery (b) Earthing (c) MCB and MCCB.

Accepted Answer

Modern electrical installations rigorously mandate essential components such as rechargeable batteries for uninterrupted emergency power, comprehensive earthing systems for absolute life safety, and automated MCBs/MCCBs to strictly prevent catastrophic thermal damage from fault currents.

Basic Electrical Engineering