©2024 TVET CDACC
071306T4EEN
ELECTRICAL TECHNICIAN (POWER OPTION) LEVEL 6
ENG/OS/PO/CR/09/6
DEMONSTRATE UNDERSTANDING OF ELECTRONICS
July/August 2024
Time: 3 Hours
TVET CURRICULUM DEVELOPMENT, ASSESSMENT AND CERTIFICATION
COUNCIL (TVET CDACC)
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WRITTEN ASSESSMENT
3 HOURS
INSTRUCTIONS TO CANDIDATE:
1. This paper consists of TWO sections: A and B.
2. Marks for each question are indicated in brackets.
3. Do not write on this question paper.
4. Answer the questions in English.
This tool consists of FOUR (4) printed pages.
Candidate should check the tool to ascertain that all the pages are printed as
indicated and that no questions are missing.
Page 1 of 4
©2024 TVET CDACC
SECTION A (40 MARKS)
Answer ALL the questions in this section.
1. In the field of science and technology, provide the definitions for the following terms:
a) Atom;
b) Electronics. (2 marks)
2. In contemporary technological contexts, outline four significant applications of electronics.
(4 marks)
3. A Bipolar Junction Transistors are used in applications of various electronic circuitry. State
three parts of the transistor. (3 marks)
4. When exploring the applications of light-emitting diodes (LEDs), several areas showcase
their versatility. List five applications of light emitting diodes. (5 marks)
5. In the realm of semiconductor physics and electronic engineering, briefly explain the
rectifying principle of a crystal diode. (2 marks
6. Silicon control rectifier and unijunction transistor are semi-conductor devices that differ in a
number of ways. Outline these differences. (4 marks)
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7. Within the domain of circuit analysis, determine the circuit frequency of a Colpitts oscillator
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given L = 100𝜇H, LRFC=0.5mH, C1=0.005𝜇F and C2 =0.01𝜇F. (5 marks)
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8. Electronics components are applied in industry technological changes, sketch the symbols
for the following electronics components:
a) Zener diode;
b) PNP transistor. (4 marks)
9. Considering semiconductor technology, list five types of special semiconductor devices.
(5 marks)
10. Filters are used for signal processing and current control, highlight four types of filters.
(4 marks)
11. Transistors are very key in electronic circuits, define the term a transistor. (2 marks)
Page 2 of 4
©2024 TVET CDACC
SECTION B (60 MARKS)
Answer any three questions in this section.
12.
a) In semiconductors, the resistivity can be modified by factors such as temperature,
impurities, or an electric field. These materials are essential components in
electronic devices, as their conductivity can be controlled to facilitate the regulation
of electric current flow. Define semi-conductor in terms of resistivity.
(2 marks)
b) A materials engineer working for a leading semiconductor manufacturing company
is tasked with developing a new generation of semiconductor chips that will power
the next wave of consumer electronics and computing devices. Explain three
important properties of semiconductors. (6 marks)
c) In electronics lab the technician illustrated various types of materials. Explain how
valence electrons determine the electrical properties of different materials.
(6 marks)
d) In semiconductor theory materials have various types of energy bands. Describe the
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three types of energy bands. (6 marks)
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13.
a) The depletion layer acts as a barrier to the flow of current under equilibrium
conditions, but it can be reduced or eliminated. This process is fundamental to the
operation of semiconductor devices such as diodes and transistors. Explain the
formation of a depletion layer. (10 marks)
b) You are a semiconductor electronics student conducting a laboratory experiment to
study the characteristics of a PN junction diode. Discuss the behaviour of a PN
junction under forward biasing. (6 marks)
c) A senior electrical engineering student working on a research project focused on the
design and optimization of semiconductor devices. Explain the following terms
briefly:
i. Breakdown voltage;
ii. Knee voltage. (4 marks)
Page 3 of 4
©2024 TVET CDACC
14.
a) Transistor amplification process forms the basis for the operation of various
electronic devices. Name four possible amplifiers. (4 marks)
b) You are an electronics engineering student learning about the applications of
transistors in various circuits. Describe the operation of a transistor as an amplifier.
(12 marks)
c) In a transistor, β = 45, the voltage across 5kΩ resistance which is connected in the
collector circuit is 5 volts. Find the base current for the common emitter connection.
(4 marks)
15.
a) There are two types of extrinsic semiconductors, their fundamental distinction
determines their electrical behaviour and makes them suitable for different
applications in electronic devices. Differentiate between these two semiconductors.
(8 marks)
b) With the aid of a diagram, differentiate between forward biasing and reverse biasing
of diodes. (8 marks)
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c) Transistors are not only used as amplifiers but also as switching devices in digital
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circuits. Explain the switching function of a transistor. (4 marks)
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