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Seat No.: Enrolment
GUJARAT TECHNOLOGICAL UNIVERSITY
PDDC SEMESTER-I EXAMINATION WINTER 2018
Subject Code:X10901 Date: 07/01/2019
Subject Name: Elements of Electrical Engineering
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt any five questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1

What is temperature co-efficient of resistance Derive equation for effect of temperature variations on magnitude of resistance.
07

Explain Kirchoff's voltage current laws with suitable examples.
07
Q.2

Explain Faraday's laws of electromagnetic induction. Where can we use this principle in electrical engineering
07

Explain how a.c. sinusoidal emf is generated? Derive its equation.
07
Q.3

Explain resonance condition in series circuit. Derive the equation of resonant frequency.
07

Explain the similarity and dissimilarity between electric circuit and magnetic circuit.
07
Q.4

A coil has resistance of 20 Ω when mean temperature is 20 °C and 30 Ω when mean temperatures is 60 °C. Find mean temperature rise when resistance is 25 Ω and surrounding temperature 25 °C.
07

Define Frequency Cycle Amplitude Form factor Peak factor Power factor Average value.
07
Q.5

Explain how we can obtain hysteresis loop for magnetic material. Which factors are responsible for hysteresis loss?
07

Derive the relation between line voltage phase voltage, line current phase current in delta connection.
07
Q.6

Explain methods to solve a.c. parallel circuits.
07

Explain the phenomena of A.C. through pure capacitor with circuit and vector diagram. Also prove that active power consumption is zero.
07
Q.7

Explain charging and discharging of capacitor.
07

Define RMS value. Derive expression for RMS value of a.c. current.
07