# Basic Electrical Engineering(3110005)

BE | Semester 1
Winter - 2019|11-01-2020
Total Marks 70

## Q1 (a) State Ohm’s law and Kirchhoff’s Laws in context with DC circuits.

Unit : DC Circuits |  Topic : Kirchoff’s current and voltage laws

## Q1 (b) A 100V, 60Watt bulb is to be operated from a 220V supply. What is the resistance to be connected in series with the bulb to glow normally ?

Unit : DC Circuits

## Q1 (c) Derive an expression for equivalent resistances of a star connected network to transform into a Delta connected network.

Unit : DC Circuits |  Topic : analysis of simple circuits with dc excitation

## Q2 (a) State Thevenin’s and Norton’s Theorems.

Unit : DC Circuits |  Topic : Thevenin and Norton Theorems

## Q2 (b) Compare series and parallel resonance in ac circuit.

Unit : AC Circuits |  Topic : Series and parallel resonance

## Q2 (c) A single-phase R-L-C circuit having resistance of 8 $\mathrm{\Omega }$ , inductance of 80mH and capacitance of 100µF is connected across single phase ac 150 V, 50Hz supply. Calculate the current, power factor and voltage drop across inductance and capacitance.

Unit : AC Circuits |  Topic : Analysis of single-phase ac circuits consisting of R, L, C, RL, RC, RLC combinations (series and par

## Q2 (c) Derive an expression for the voltage across the capacitor during charging through the resistor at any instant . Assume that RC series circuit is connected across a DC supply of voltage V.

Unit : DC Circuits |  Topic : Time-domain analysis of first-order RL and RC circuits

## Q3 (a) Define the following terms in connection with AC waveforms : - (1) Q-Factor (2) Power Factor (3) Form factor.

Unit : AC Circuits |  Topic : Representation of sinusoidal waveforms

## Q3 (b) Draw impedance triangle, Voltage triangle, Power triangle for single phase R-L series circuit.

Unit : AC Circuits |  Topic : Analysis of single-phase ac circuits consisting of R, L, C, RL, RC, RLC combinations (series and par

## Q3 (c) Derive the relationship between Phase and Line values of voltages and currents in case of 3-phase Star- connection.

Unit : AC Circuits |  Topic : Three phase balanced circuits

## Q3 (a) Define the terms: - 1. Real power 2. Reactive power 3. Apparent power.

Unit : AC Circuits

## Q3 (b) Derive the EMF equation of single-phase transformer.

Unit : Transformers |  Topic : Construction and working principle of single phase and three phase transformers

## Q3 (c) With neat circuit diagram and a phasor diagram prove that two-watt meters are sufficient to measure total power in 3-phase system.

Unit : AC Circuits |  Topic : Power measurement in three phase circuits

## Q4 (a) Explain working principle of single-phase Transformer.

Unit : Transformers |  Topic : Construction and working principle of single phase and three phase transformers

## Q4 (b) Give Merits, Demerits and Applications of Induction Motor.

Unit : Electrical Machines

## Q4 (c) Explain in detail the construction of an Alternator.

Unit : Electrical Machines |  Topic : Construction and working of Synchronous generators

## Q4 (a) Explain working principle of D.C. Motor.

Unit : Electrical Machines |  Topic : Construction and working of Separately excited DC motor

## Q4 (b) Compare poly phase Induction Motor and single-phase Induction Motor.

Unit : Electrical Machines

## Q4 (c) Explain Generation of Rotating Magnetic Field in 3-phase Induction Motor with diagrams and equations.

Unit : Electrical Machines |  Topic : Generation of rotating magnetic fields.

## Q5 (a) Classify different types of cables with reference to voltage and insulation materials.

Unit : Electrical Installations |  Topic : Types of Wires and Cables

## Q5 (b) Explain the terms : - 1. Residual magnetism 2. Coercive Force.

Unit : Transformers

## Q5 (c) Explain the process of charging and discharging of Lead acid cell.

Unit : Electrical Installations |  Topic : Types of Batteries, Important Characteristics for Batteries