# EEC125 exam

```ABRAHAM ADESANYA POLYTECHNIC, IJEBU-IGBO
FIRST SEMESTER EXAMINATION NDI 2016/2017 SESSION
SCHOOL OF ENGINEERING
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COURSE TITLE:
COURSE CODE:
LEVEL:
INSTRUCTION:
ELECTRICAL ENGINEERING SCIENCE 1
EEC115
TIME: 2:00 HRS
ND I ELECTRICAL/ELECTRONIC ENG. &amp; COMPUTER ENGINEERING
1a. Define energy and state its various form
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b. The power expended in a certain resistor is given by I R. If the power expended in the
resistor
is 175W when the current is 5A, Calculate the power in the resistor when,
(i) Both current &amp; resistance are double.
(ii) Current is half and resistance double.
(iii) When current is double and resistance half.
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2a. Define the following terms and state the unit in which they are measured: (i)Electric
current
(ii)Potential
Difference
(iii)Electromotive
force
(iv)Resistance
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b. Two metre resistance wire of cross sectional area of 0.5mm2 has a resistance of 2.2Ω.
Calculate (i) the resistivity of the material
(ii)the length of the wire which when connected in parallel with the 2m length, will give a
resistance of 2.0 Ω
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3a. Define Capacitance of a capacitor and list the different types
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b. Two capacitors, A and B, of capacitance 2&micro;F and 4&micro;F respectively, are connected in series to
a dc supply; the charge store by each capacitor is 0.16mc. Determine:
(i) the p.d across each capacitor
(ii) the energy stored in each capacitor
(iii)the effective capacitance of the series combination.
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4a. State five analogies between water flow and current flow
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b. A circuit consists of a 1 Ω wire in series with a parallel arrangement of 6 Ω and 3 Ω and a p.d
of 12V is connected across the whole circuit. Calculate the current in each of the 3 wires
and the p.d across each using ohms law
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5a. For the network shown in Fig.below, find the values of the currents marked
126
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b. State kirchoff’s laws
c. Differentiate between conductor, insulator and semiconductor
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6a. Define the following terms (i)Electric field strength (ii)Electric flux density (iii)Electric
potential (iv)Electric field
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-9
-9
b. The small identical conducting spheres have charges of 2.0 &times; 10 and -0.5 &times;10
respectively. When they are placed 4 cm apart, what is the force between them ? If they are
brought into contact and then separated by 4 cm, what is the force between them ? 6mks
7a. State the coulomb’s laws of electrostatic
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b. If two batteries are connected in parallel, one of EMF 6V and internal resistance 0.5Ω and
the other of EMF 8V and internal resistance 0.6Ω, and in turn connected to an external 10Ω
resistor. Find the current in each resistor using kirchoff’s laws
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127
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