TW75
UNIVERSITY OF BOLTON
DEPARTMENT OF ENGINEERING, SPORTS AND
SCIENCES
BEng(Hons) Electrical and Electronics Engineering
SEMESTER 1 EXAMINATION 2014/2015
Introductory Electrical Principles
MODULE NO: EEE4002
Date: Monday 19 January 2015
INSTRUCTIONS TO CANDIDATES:
Time:
2.00 – 4.00pm
There are 4 questions.
Answer all questions.
All questions carry equal marks.
Individual marks are shown within the
question.
A formula sheet is given at the end of the
paper.
Page 2 of 6
Engineering, Sports and Sciences
BEng(Hons) Electrical and Electronics Engineering
Semester 1 Examination 2014/2015
Introductory Electrical Principles
Module No. EEE4002
Question 1
a) Define the following terms (1 mark for each definition):
i.
ii.
iii.
iv.
v.
vi.
vii.
viii.
ix.
x.
Electric charge
Electric current
Electromotive force
Potential difference
Magnetic flux density
Electromagnetic induction
Motional electromotive force
Internal resistance
Ideal ammeter
Ideal voltmeter
b) Consider the following circuit, which consists of a conducting bar of length ℓ
sliding with constant velocity v along two fixed parallel conducting rails connected
via a resistor R. If the direction of the magnetic field B is pointing from the viewer
to the paper and x is the distance that the conducting bar is covering, then:
i.
ii.
iii.
iv.
Draw the direction of the magnetic force FB (1 mark)
Draw the direction of induced current I (2 marks)
If the conducting bar has an internal resistance Rint, what electrical circuit
is this arrangement equivalent to? (2 marks)
What would be the magnetic flux ΔΦ, the induced electromotive force ΔV,
and induced current I? (10 marks)
Please turn the page
Page 3 of 6
Engineering, Sports and Sciences
BEng(Hons) Electrical and Electronics Engineering
Semester 1 Examination 2014/2015
Introductory Electrical Principles
Module No. EEE4002
Question 2
a) Define Kirchhoff’s voltage and current law (3 marks)
b) Define the superposition principle (4 marks)
c) Apply the superposition principle to the following voltage-divider in order to find Vp
(18 marks)
Please turn the page
Page 4 of 6
Engineering, Sports and Sciences
BEng(Hons) Electrical and Electronics Engineering
Semester 1 Examination 2014/2015
Introductory Electrical Principles
Module No. EEE4002
Question 3
a) Find the Norton equivalent to the following circuit (10 marks)
b) In the following circuit, find the value of load resistance RL that will provide the
maximum power delivered to the load. Also calculate the maximum power PL across
the load. (15 marks)
Please turn the page
Page 5 of 6
Engineering, Sports and Sciences
BEng(Hons) Electrical and Electronics Engineering
Semester 1 Examination 2014/2015
Introductory Electrical Principles
Module No. EEE4002
Question 4
A 50-Ω resistor, a 75-Ω inductive reactance, and a 100-Ω capacitive reactance are connected
in series (Fig. 1) and then in parallel (Fig. 2) across a typical UK AC power line of 230 V and
50 Hz, as shown in the following figures. For each circuit:
a) Draw the appropriate phasor diagram (5 marks)
b) Determine the values of:
i.
Total current Itot and total voltage Vtot (5 marks)
ii.
Phase angle θ ≠ 0 between reference phasor and Itot or between reference
phasor and Vtot (5 marks)
iii.
Impedance Z (5 marks)
c) Determine if the circuit is inductive or capacitive and explain why (5 marks)
Fig. 1: RLC circuit in series
Fig. 2: RLC circuit in parallel
End of questions
Page 6 of 6
Engineering, Sports and Sciences
BEng(Hons) Electrical and Electronics Engineering
Semester 1 Examination 2014/2015
Introductory Electrical Principles
Module No. EEE4002
APPENDIX: Formula Sheet
The following symbols in the formulae have their standard meaning:
Ohm’s law: V  IR
Power: P  IV
Magnetic flux: Φ = BA
Induced voltage: V = ΔΦ/Δt
Magnitude of the Reactance of Inductor L: X L  2fL
Magnitude of the Reactance of Capacitor C: X C 
Velocity: v = Δx/Δt
Pythagorean theorem: c2 = a2 + b2
1
2fC