# Electricity Paper 2 Questions and Answers - KCSE 2022 Prediction

INSTRUCTIONS TO CANDIDATES

• Non-programmable silent electronic calculators are allowed for use
• This paper consists of 5 EXERCISES
• Each exercise should be done in 30 MINUTES

## Questions

EXERCISE 1

Using the components, materials and equipment provided, perform the following tasks

1. Connect the figure as shown below. Let the examiner check your work (6 marks)
2. Close the switch. Adjust the potentiometer to obtain voltage reading shown in the table below. For each voltage obtained, measure and record the corresponding current values (5 marks)
 Voltage(V) 0 0.5 0.7 0.9 1.3 1.7 Current(mA)
3. Plot a graph of current against voltage. (6 marks)
4. From the graph
1. Determine the resistance when the voltage is 1.3V
2. Give a reason for the shape of the graph (3 marks)

EXERCISE 2

Using the components, materials and equipment provided, carry out the following tasks:

1. Connect the circuit as shown in the figure below

Let the examiner check your work. (5 marks)
2. Adjust Vcc to the values shown in the table below and for each voltage value measure and record the corresponding value of the collector current, Ic (6 marks)
 Vcc 9 7 5 3 1 0.5 Ic(mA)
3. Repeat step in (b) above for the values shown in the table below and complete the table
 Vcc 10 8 6 4 2 0.5 Ic(mA)

From the results obtained in (b) and (c) above, make two comments about the collector current Ic. (4 marks)
4. State two factors that determine the value of collector current (2 marks)

EXERCISE 3

Using the tools, materials and equipment provided, carry out the following tasks:

1. Terminate the three-core flexible cable to the top plug and iron box (15 marks)
2. Turn the thermostat switch to ON position, measure and record the values of resistance between;
1. Live and Neutral at plug………Ohms
2. Live and earth at plug………...Ohms
3. Earth at plug and iron box body……..Ohms
4. Neutral at plug and at iron box……….Ohms
(5 marks)

EXERCISE 4

Using the tools, material and equipment provided, fabricate the stand as shown in the figure below. (20 marks)

EXERCISE 5

The figure below shows the layout of a final circuit. Using PVC sheathed cables, install the lamps to controlled by one-way switch (20 marks)

## Confidential

 NO ITEM TYPE No. OF ITEMS PRICE(KSH) 1 Diodes 1n4007 8 100 2 Potentiometer 1kΩ 8 300 3 Resistor 1kΩ4.7kΩ10kΩ 888 100100100 4 Switch Power Rocker SPST SwitchOne-way, one gang​ 88 400500 5 Iron Box Soarin Electric Dry Iron Box 4 4000 6 Top plug 4 200 7 Cables Three core flexible cable1.5mm PVC twin earth cable 4 pieces2.4 m 2503000 8 Metal sheet 1.5 x 1.0 m 1 Sheet 9 Junction box 8 900 10 Transistors BC547 10 100 100 Lamp holder 10 500 11 Lamps 50W Filament lamps 4 250 Total 10 050

## Marking Scheme

EXERCISE 1

 Area to be marked Maximum Score Candidates score a Correct connection 6 marks b Correct value of current in (mA) 5 marks c Smooth graph of current against voltage 6 marks d Correct value of resistance at 1.3V and reason 3 marks Total 20 Marks

EXERCISE 2

 Area to be marked Maximum Score Candidates Score a Correct circuit connection on breadboard 5 b Correct value for current Ic at set voltage 6 c Correct value of current Ic at given voltages 3 d Correct comment about the collector current Ic 4 e Correct factors that determine the value of collector current Ic 2 Total 20

EXERCISE 3

 Area to be marked Maximum score Candidates score Terminating Live (Brown) cable to line terminal of the plug and iron box correctlyTerminating the Neutral (blue) cable to the neutral terminal of the plug and iron box correctlyTerminating earth (yellow-green) cable to the earth terminal of the plug and iron box correctly 555 Correct value of resistance between Live and Neutral at plugCorrect value of resistance between Live and earth at plugCorrect value of resistance between Earth at plug and iron box bodyCorrect resistance between the Neutral at plug and at iron box .22. Total 20

EXERCISE 4

 Area to be Marked Maximum Score Candidate Score Correct marking on the metal 6 Smooth bending of the metals 8 Accurate drilling of the metals 3 Assembling the metal parts 2 Smooth and good finishing 1 Total 20

EXERCISE 5

 Area to be marked Maximum Score Candidate Score Wiring diagram 4 Firm mounting of the accessories provided 2 90° bending of cables 3 Uniform spacing of cable clips 1 Termination 8 Functioning of the installed circuit 2 Total 20

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