THE KENYA NATIONAL EXAMINATIONS COUNCIL
CRAFT CERTIFICATE IN INFORMATION TECHNOLOGY BASIC ELECTRONICS – July 2023
Time: 3 Hours
INSTRUCTIONS TO CANDIDATES:
1. This paper consists of TWO sections: A and B.
2. Write your Name and Index Number in the answer booklet provided.
3. Answer ALL questions in Section A and ANY FOUR questions from Section B.
4. Answer all questions in English.
This paper consists of 6 printed pages.
Candidates should check the question paper to ensure that all the pages are printed as indicated and no questions are missing.
© 2023 The Kenya National Examinations Council
Turn Over
SECTION A: (40 Marks)
Answer ALL questions in this section.
1. Outline four uses of computer cache memory.
Speeds up data access by storing frequently used information close to the CPU. Reduces latency by minimizing the time required to fetch data from main memory. Minimizes workload on main memory, improving its efficiency and longevity.
Enhances overall system performance, making programs run faster.
2. Explain each of the following terms as used in Electronics:
(a) Charge:
The property of subatomic particles like electrons and protons that causes them to experience a force in an electric field. It is measured in coulombs (C).
(b) Joule:
The unit of energy. It is the work done when a force of 1 newton moves an object 1 meter.
1 Joule = 1 N•m.
3. Figure 1 represents a simple DC circuit. Use it to answer the question that follows.
(i) Explain two uses of the part labeled (i):
Voltage Regulation: Ensures consistent voltage across circuit components.
Current Limiting: Protects components by preventing excess current.
4. With the aid of a sketch, outline a purely capacitive circuit.
A purely capacitive circuit consists of a capacitor connected to a voltage source. The voltage leads the current by 90°.
(Sketch: Capacitor in series with a voltage source)
5. Differentiate between primary and secondary computer memory.
Primary Memory Secondary Memory
Volatile; loses data when power is off Non-volatile; retains data permanently
Directly accessible by the CPU Requires input/output devices for access
Examples: RAM Examples: HDD, SSD
6. Explain two advantages of using Excess-3 code.
Error Detection: Facilitates easy identification and correction of errors in digital systems.
Simplified Arithmetic: Simplifies the execution of arithmetic operations.
7. Explain two circumstances under which fixed resistors are most applicable in the construction of electrical components.
Stable Load Requirements: When a specific, unchanging resistance is needed in a circuit. Non-variable Conditions: For circuits operating under stable conditions without the need for adjustment.
8. Define each of the following terms as used in Electronics:
(a) Cycle: One complete oscillation in an alternating current waveform.
(b) Peak: The maximum amplitude or value of a waveform.
9. Evaluate each of the following binary arithmetic operations:
(a) 11101100 + 10101100
Solution:
Step 1: Align the binary numbers:
Step 2: Perform binary addition:
Result: 110110000
(b) 111011100 ÷ 100
Solution:
Convert to decimal:
1110111002 = 47610
1002 = 410
Perform division:
476 ÷ 4 = 119
Convert back to binary:
11910 = 11101112
Answer: 1110111
10. Draw a logic circuit for the Boolean expression X = A⋅ B + C.
(Sketch: AND gate for A⋅ B, OR gate combining A⋅ B and C.)
SECTION B: (60 Marks)
Answer ANY FOUR questions from this section.
15. (a) (i) Explain two disadvantages of using holographic memory.
High Cost of Production: Requires sophisticated and precise technology, making it expensive. Complex Alignment: Data retrieval depends on precise positioning of optical systems, which are sensitive to physical disturbances.
(ii) Differentiate between laminated core transformer and autotransformer.
Laminated Core Transformer Autotransformer
Uses laminated cores to reduce eddy currents Uses a single winding for voltage step-up/down
Separate windings for primary and secondary circuits Primary and secondary circuits share winding
Larger and heavier Smaller and compact
(b) (i) Determine the octal equivalent of the Gray code number 111011012.
Convert Gray code to binary: 10101001
Convert binary to octal: 251
(ii) Draw multi-input logic gates for:
1. A⋅ B⋅ C: Use a 3-input AND gate.
2. (A + B)⋅ (C + D): Use OR gates for A + B and C + D, followed by an AND gate.