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EAM601S - ELECTRICITY AND MAGNETISM - 1ST OPP - JUNE 2022 |
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NAMIBIA UNIVERSITY
OF SCIENCE AND TECHNOLOGY
FACULTY OF HEALTH, APPLIED SCIENCES AND NATURAL RESOURCES
DEPARTMENT OF NATURAL AND APPLIED SCIENCES
QUALIFICATION: BACHELOR OF SCIENCE
QUALIFICATION CODE: 07BOSC
COURSE CODE: EAM601S
SESSION: JUNE 2022
DURATION: 3 HOURS
LEVEL: 6
COURSE NAME: ELECTRICITY AND MAGNETISM
PAPER: THEORY
MARKS: 100
EXAMINER (S)
MODERATOR:
FIRST OPPORTUNITY EXAMINATION QUESTION PAPER
MR EMMANUEL EJEMBI
MR VAINO INDONGO
INSTRUCTIONS
1. Write all your answers in the answer booklet provided.
2. Read the whole question before answering.
3. Begin each question on a new page.
PERMISSIBLE MATERIALS
Scientific Calculator
THIS QUESTIONS PAPER CONSISTS OF 6 PAGES (Including this front page)
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SECTION A
QUESTION 1
[30]
Short Answer Question Types: Each question in this section carries two marks
1.1 Positive charge is obtained when;
(2)
a. cellulose acetate is rubbed with silk —b. polythene is rubbed with silk
c. ebonite rod is rubbed with fur
d. glass rod is rubbed with fur
1.2 The electric field intensity is given by ——————_—-.
(2)
a. Force
Charge
b.Cha—rg=e
Force
«. Charge X Force
d../Charge xX Force
1.3 Current is the rate at which charges move through
(2)
a.aninsulator b. aconductor c.voltage d.ampere
1.4 Static electricity is produced due to;
(2)
a. friction b.conduction c. insulation d.bothaandc
1.5 The S.I unit of electric field is;
(2)
a.Am-! b.NC71 c.Cm} d.Cm~?
1.6 The instrument used in the measurement of voltage is;
(2)
a. voltmeter
b. wheatstone bridge
c. potentiometer
D. ammeter
1.7 A work of 70 J is done in transferring 20 C of charge from a point B to a point Ain an
(2)
electric field. Calculate the potential difference between A and B.
a 25V b. 1.5V
é& 35V
d. 4.0V
1.8 When a charge, q is released from rest in a uniform electric field, Eset up betweentwo (2)
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oppositely charged plate with respect to vertical distance, y, what is the equivalent
expression of the kinetic energy of the falling charge?
a.mv?/2 b.2Ey c. qEy d.Eq
1.9 When an electron, e, is projected horizontally into a uniform electric field, E, with an
(2)
initial velocity, Vo, with an attraction towards positive charge at time, t, what is the
value of the horizontal displacement?
a. eEt? b.at? c.Vot d.eEt.
1.10 Capacitors have many applications in electrical circuit including the following except. (2)
a. turning in radio circuit b. eliminating of spark in switches
c. rectification of coil in atransformer d. blocking noise in a.c. amplifies
1.11 The parallel plates of an air-filled capacitor are everywhere 1.0 mm apart. What must (2)
the plate area be if the capacitor is to be 1.0 F?
a. 1.1 x 108 m?
b. 1.2 x 108 m?
c. 1.3 x 108 m?
d. 1.4 x 108 m?
1.12 The instrument used in the measurement of magnetic force is;
(2)
a. magnetic flux b. magnetometer c. magnetic filling | d. iron filling
1.13 The ability of one coil to induce current in the nearby coil by the phenomenon of
(2)
Induction when the current in the first coil changes is called
a. self-induction
—_b. electromagnetic induction c. mutual induction
d. inductance
1.14 An electrical device that convert converts mechanical energy into electric energy
(2)
or vice versa is called
a. converterb.dynamo c.motor d. generator.
1.15 The root mean square value of the voltage in an ac circuit is:
(2)
a. 0.637 Vmax b.0.707 Vmax C.2Vmax d. V2 Vinax
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SECTION B
QUESTION 2
[15]
2.1 Define electrostatic.
(2)
2.2 List the two methods of charging the gold leaf electroscope.
(2)
2.3 State three examples of a field.
(6)
2.4 The concentration of charge on a conductor is such that its strength is 6uC and
(5)
the surface area is 31m”. What is its surface density?
QUESTION 3
[15]
3.1 Define electric resistance.
(2)
3.2 State three laws of resistances in series.
(3)
3.3 Write down the equation for the electric field due to a uniformly charged wire of length and
(5)
define the various parameters.
3.4 In the figure below, find the resistance from point a to point b.
(5)
a
90
2.73.9
@
Lf
beiccaened
“oXOY U7
L__|
@
59
b
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QUESTION 4
[15]
4.1 Define electric potential difference.
(2)
4.2 List three properties of electric field intensity.
(3)
4.3 What do you understand by the term equipotential surface?
(4)
4.4 In the Millikan experiment, an oil drop carries four electronic charges and has a mass
of 1.8 x 10° g. It is held almost at rest between two horizontals charged plates 1.8 cm
apart. What voltage must there be between the two charged plates? (Take electron
charge e = 1.60 x 10°"9 C)
(6)
QUESTION 5
[15]
5.1 State Lenz’s law of electromagnetic induction.
(2)
5.2 What did you understand by the term dynamo?
(3)
5.3 Explain the term self-inductance.
(3)
5.4 A coil of inductance 0.2 H and 1.0 (© resistance is connected to a 90 V source.
(7)
(i) At what rate will the current in the coil grow at the instant the coil is connected to the
source?
(ii) What is the current when it is growing at a rate of 100 A/S ?
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QUESTION 6
[10]
6.1 Define the following terms:
(2)
(i) Inductive reactance
(ii) Capacitive reactance.
6.2 Draw an alternating circuit that involved a resistor, an inductor, and a capacitor
connected in series with an ac source. What is the general name for the circuit?
(3)
6.3 The voltage output of a generator is given by Av = 200sinwt. Find
the rms current in the circuit when this generator is connected to a 100 () resistor.
(5)
END!