Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2019 Summer 1st And 2nd Sem (New And SPFU) 2110005 Elements Of Electrical Engineering Previous Question Paper
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?I &II (NEW) EXAMINATION ? SUMMER-2019
Subject Code: 2110005 Date: 20/06/2019
Subject Name: Elements of Electrical Engineering
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Question No.1 is compulsory. Attempt any four out of remaining six questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1 Objective Question
Mark
(a) Answer the following multiple choice questions. 07
1. Which of the following relations is incorrect?
(a) P=V
2
G (b) V= ?PR (c) G=P/I
2
(d) I=?(P/R)
P= power, V= Voltage, I= current, R=resistance, G=conductance
2. Ohm?s law is not applicable to
(a) ac circuit (b) dc circuit (c) semi-conductor (d) linear circuits
3. Which of the following is a vector quantity?
(a) electric charge (b) electrical potential
(c) electric field intensity (d) none of the above
4. Which law states that the induced e.m.f. and current always oppose
the cause of producing them?
(a) Lenz (b) Fleming (c) Faraday (d) Maxwell
5. Which of the following frequencies has the longest time period?
(a) 10 kHz (b) 1 kHz (c) 10 Hz (d) 1 Hz
6. The resonance frequency for the series RLC circuit where, R=100 ?,
L = 80 mH, C = 3160 pF.
(a) 15 kHz (b) 10 kHz (c) 8 kHz (d) 12 kHz
7. Series connection of cells
(a) increases the efficiency (b) increases the voltage output
(c) increases the current output (d) decreases the internal resistance
(b) Answer the following 07
1. Give reason why are all equipments connected in parallel to the
supply.
2. If resistance of each branch is 3 ? in a delta connected load, what
would be the resistance of each branch in star equivalent?
3. Give relationship between electric flux density and electric field
intensity.
4. What do you mean by capacitance? Give its unit.
5. State Fleming?s left hand rule.
6. Define rms value.
7. Differentiate between phase and line voltages in three phase circuits.
Q.2 (a) State and Explain Kirchhoff?s laws in context with DC circuits. 03
(b)
Calculate the current I through 25 ? resistance in the circuit shown
below if Input I1 of 5 mA is applied using a current source.
04
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Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?I &II (NEW) EXAMINATION ? SUMMER-2019
Subject Code: 2110005 Date: 20/06/2019
Subject Name: Elements of Electrical Engineering
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Question No.1 is compulsory. Attempt any four out of remaining six questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1 Objective Question
Mark
(a) Answer the following multiple choice questions. 07
1. Which of the following relations is incorrect?
(a) P=V
2
G (b) V= ?PR (c) G=P/I
2
(d) I=?(P/R)
P= power, V= Voltage, I= current, R=resistance, G=conductance
2. Ohm?s law is not applicable to
(a) ac circuit (b) dc circuit (c) semi-conductor (d) linear circuits
3. Which of the following is a vector quantity?
(a) electric charge (b) electrical potential
(c) electric field intensity (d) none of the above
4. Which law states that the induced e.m.f. and current always oppose
the cause of producing them?
(a) Lenz (b) Fleming (c) Faraday (d) Maxwell
5. Which of the following frequencies has the longest time period?
(a) 10 kHz (b) 1 kHz (c) 10 Hz (d) 1 Hz
6. The resonance frequency for the series RLC circuit where, R=100 ?,
L = 80 mH, C = 3160 pF.
(a) 15 kHz (b) 10 kHz (c) 8 kHz (d) 12 kHz
7. Series connection of cells
(a) increases the efficiency (b) increases the voltage output
(c) increases the current output (d) decreases the internal resistance
(b) Answer the following 07
1. Give reason why are all equipments connected in parallel to the
supply.
2. If resistance of each branch is 3 ? in a delta connected load, what
would be the resistance of each branch in star equivalent?
3. Give relationship between electric flux density and electric field
intensity.
4. What do you mean by capacitance? Give its unit.
5. State Fleming?s left hand rule.
6. Define rms value.
7. Differentiate between phase and line voltages in three phase circuits.
Q.2 (a) State and Explain Kirchhoff?s laws in context with DC circuits. 03
(b)
Calculate the current I through 25 ? resistance in the circuit shown
below if Input I1 of 5 mA is applied using a current source.
04
(c) What do you mean by resistance temperature co-efficient? Derive &
obtain the expression ?2 = 1/(1/?1 + (t2 - t1)) with usual notation.
07
Q.3 (a) State and explain Coulomb?s law of electrostatics. 03
(b) Derive an expression for co-efficient of mutual coupling between two
coils having self-inductances of L1 and L2 with usual notations.
04
(c) Two square conducting plates having cross sectional area of 2500 cm
2
and 1 cm distance between them are connected across a 600 V supply
voltage. They have a dielectric 0.8 cm thick having a relative
permittivity of 4 between them. The remaining space is filled with air.
Calculate the capacitance of the condensor and the energy stored in it.
07
Q.4 (a) Define: (1) Magnetic flux density (2) Magnetic field intensity (3)
Reluctance.
03
(b) A circular ring of a mild steel has a diameter of 20 cm and 2 mm side
air gap. The cross sectional area is 3.2 cm
2
. Estimate the mmf
required to establish a flux of 0.6 mWb. Assume relative permeability
of mild steel = 900.
04
(c) Define the co-efficient of coupling. Derive the relationship between
self-inductance and mutual-inductance.
07
Q.5 (a) Give comparison between series and parallel resonance. 03
(b) An alternating voltage is v = 100 sin 100t. Find (i) Time period and
frequency (ii) Angular velocity (iii) Form factor (iv) Peak factor.
04
(c) Prove that current in purely capacitive circuit leads its voltage by 90?
and average power consumption in pure capacitor is zero.
07
Q.6 (a) Define power factor. Enlist the demerits of low power factor. 03
(b) A delta connected balanced 3-phase load is supplied from a 3-phase
400 V supply. The line current is 20 A and the power taken by the
load is 10,000 W. Find (i) impedance in each branch (ii) the line
current, power factor and power consumed if the same load is
connected in star.
04
(c) Show that for star connection of three phase circuit, the line voltage is
equal to 1.732 times the phase voltage whereas line current is equal to
phase current. Also draw phasor diagram to support your answer.
07
Q.7 (a) Give classification of various types of lighting schemes and explain
any two.
03
(b) Explain the construction of cable with neat diagram. 04
(c) What do you mean by earthing? Analyze earthing concept with the
help of a device ELCB (Earth leakage circuit breaker) used at our
residence.
07
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This post was last modified on 20 February 2020