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ADISS ABABA SCIENCE TECHNOLOGY ENGINEERING AND MATHEMATICS CENTER

Electronics Laboratory Manual Curriculum

Grade 9 and 10

2012

Compiled By:-ANTENEH FISSEHA

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Curriculum

9-10 Electrical and Electronics Lab. Experiments

Topics Sub Topics Periods

Introduction Introduction Safety rules and regulation 1

Electrical Symbols Measuring Instruments

How to use Voltmeter How to use Ammeter How to use Ohm meter How to use Oscilloscope

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Electrostatics 1. Electric charge2. Electric force and field3. Electroscope4. Electric potential5. Capacitor and capacitance.

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Current Electricity 6. Law and Kind of Circuits Electric circuit Electric current Ohms law Kerchiefs current law Kerchiefs voltage Law Series circuit Parallel Circuit

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Introduction to Electronics

Conductor, insulator and semiconductors 1

Components demonstration Inductor Integrated Circuits(IC’s) Diode LED LDR Transistor

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Electromagnetism 7. Magnet Types of magnet Poles of magnet Properties of magnet

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8. Lines of force of magnet 2

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Compass Properties of lines of force

of magnet9. Electromagnetic induction 110. Motor effect

Constructing simple motor 2

11. Projects

Lab experiment has to contain

Experiment title Objective Brief Theory Required Material Circuit Diagram Procedure Data Collection and Analysis Questions Result and discussion Conclusion

Experiment 1- Use digital test equipments.

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Objective:- Using Digital Multimeter

Brife Therory:-1. Using digital voltmeters2. Using digital ammeters3. Using digital ohmmeters4. Using digital Multimeters

Material Reqired:-

Digital Multimeter, Test Leads

1.1 Procedure using Digital voltmeter

1. Identify the measurable quantity (i.e voltage) weather AC or DC.2. If the measurable quantity is AC select the knob on AC position and the range depend

on the measured value as shown in the figure below.

Fig. 1 AC digital voltmeter for measuring voltage across the AC supply.

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Where:-

1. Selection knob what Variables to be measured2. Range selection3. Probes (leads)4. The quantity to be measured (I.e. ac power supply)5. LCD (display unit)

1. If the measurable quantity is DC select the knob on DC position and the range depend on the measured value as shown in the figure below.

The leads are connected

Red leads connect on the positive terminal to the circuit.

COM (Black) leads connect to the negative terminal to the circuit. As shown in the figure below.

Fig. 2a. DC digital voltmeter for measuring voltage across the battery.

2. If the polarity error not connected properly, it indicates a negative sign (-) on the display screen, you should change the position of the leads.

3. To measure the voltage across the resistance, we must connect the voltmeter parallel to the resistance as shown below.

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Fig.2b. Voltage measured across the resistance.

4. Record the value what you read from the voltmeter.

CAUTIONS To avoid unnecessary damage you must careful the following listed pointes. Disconnect circuit power and discharge all high-voltage capacitors (if there is a capacitor

in the circuit) before testing resistance, continuity, diodes, or capacitance. Use the proper terminals, function, and range for your measurements. Before measuring current, check the meter's fuses and turn power off to the circuit

before connecting the meter to the circuit. Before rotating the range switch to change functions, disconnect test leads from the

circuit under test. When you measure the voltage always you must connect the voltmeter across the

component to be measured.

1.2 Procedure using Digital Ammeter

1. Identify the measurable quantity (i.e. current ) weather AC or DC.2. If the measurable quantity is DC select the knob on DC position and the range depend

on the measured value as shown in the figure below.

Fig. 4 Connection to measure current flow through the resistance.

3. If the measurable quantity is DC select the knob on DC position and the range depend on the measured value as shown in the figure below.The leads are connected

Red leads connect on the positive terminal to the circuit.

COM (Black) leads connect to the negative terminal to the circuit. As shown in the figure below.

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4. If the polarity error not connected properly, it indicates a negative sign (-) on the display screen, you should change the position of the leads.

5. To measure the current through the resistance, we must connect the ammeter series the resistances as shown below.

Experiment 2 -Measuring Resistance.

Objective:-Measuring resistance of resistor using color coding method.

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Brief theory:-

The electronic color code is used to indicate the values or ratings of electronic components, very commonly for resistors, but also for capacitors, inductors, and others.

Resistance slowdowns the flow of charges in the circuit. We use the symbol R to show the resistance and it is measured in unit is called ohms with the symbol Ω.

Procedure

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To distinguish left from right there is a gap between the C and D bands.

band A is first significant figure of component value (left side) band B is the second significant figure band C is the decimal multiplier band D if present, indicates tolerance of value in percent (no band means 20%)

For example, a resistor with bands of yellow, violet, red, and gold will have first digit 4 (yellow in table below), second digit 7 (violet), followed by 2 (red) zeros: 4,700 ohms. Gold signifies that the tolerance is ±5%, so the real resistance could lie anywhere between 4,465 and 4,935 ohms.

All coded components will have at least two value bands and a multiplier; other bands are optional.

Experiment 2- Electrostatics

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Objective:-Verifying electrostatics Effect.

Brief Theory:-

Electrostatics is the study of electric charge which is static (not moving).All object surrounding us (including people) contain large amount of electric charge. There are two types of electric charge: positive charge and negative charge. If the same amount of electric charge brought together, they neutralize each other and there is no net charge. Neutral objects contain equal number of positive and negative charge. However, if there is a little bite more of one type of charge than the other on the object then the object is said to be electrically charged. charge is measured in units is called coulombs(C).A coulombs of charge is very large charge. In electrostatics we therefore often work with charge in microcoulombs (1μC=1x10-6C) and nano coulombs (1nC=1x10-9C).

Important: charge, just like Energy, cannot be created or destroyed. We say charge is conserved.

Force between charges.

The force exerted by non-moving (static) charge on each other is called electrostatic force. The electrostatic fore between like charge repulsive and opposite(unlike) charges is attractive. This is different form gravitational force which is only attractive.

Required material

Golden leaf Electroscope. Glass rod and rubber balloon. Piece of silk and fur.

Procedure.

1. Take a inflated rubber balloon and rub it with piece of silk or hair. Just bring rubber balloon close to Electroscope Hold it for a few second.

2. I f you then bring another glass rod which you have also charged the same way next to it.

3. You will see the gold leaf apart each other i.e. it is repelled.4. You Take plastic rod rub it with a piece of fur and then bring to electroscope.

Measure the magnitude of the charged object.5. Take a inflated rubber balloon and close contact to a piece of rough paper i.e. it is

attracted.

Question

1. Convergence is more when …………………2. Is it possible to determine polarity of charged object in Electroscope? If no why?

Conclusion

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Experiment 3 - Ohm’s law

Objective:-In this experiment we will look at the relationship the current going through the resistor and the potential difference (voltage) across the same resistor.

Brief theory:-An electric circuit is closed path (with no break or gap) along which electric charge (electrons) flows powered by an energy source. Some Components which can be found in electrical circuits includes light bulbs, batteries, connecting leads, resistor, switch etc. It is more important to know what their symbols are and how to represent them in circuit diagrams. Below is a table with the items and their symbols.

A physical circuit is the electric circuit you create in real components and circuit diagram is diagram which uses a symbol to represent the different components in physical circuit.

Definition Ohms Law

The amount of electric current through the conductor, at constant temperature, in a circuit is proportional to the voltage across the conductor. Mathematically, Ohms law is written as

V=R.I.

Material required

Cell or DC source Resistor Voltmeter Ammeter Connecting leads

Circuit Diagram

Procedures

a) Set up the circuit according to the circuit diagram.b) Fill the following table by measuring appropriate values.

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Voltage,v (V) Theoretical Ampere,I(A)

Practical Ampere,I(A)

1.534.567.59

c) Get your teacher to check the circuit before turning the power on.d) Measure the current.e) Increase voltage in the multiple of 1.5V to the circuit and measure the current again.f) Repeat until you have 6 data and completed table.g) Draw the graph Voltage in y-axis vs Current in x-axis.

Questions

1) Does your experiment result verified Ohm’s Law?2) What type of graph you obtain (straight line, parabola, other curve) and what it

represent?

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EXPERIMENT 4 - SERIES & PARALLEL CIRCUITS

Brief Theory:

This experiment extends the application of Ohm’s Law to two or more components connected in simple series and parallel circuits. A series circuit is a circuit in which resistors are arranged in a chain, so the current has only one path to take. The current is the same through each resistor. The total resistance of the circuit is found by simply adding up the resistance values of the individual resistors.

A parallel circuit is a circuit in which the resistors are arranged with their heads connected together, and their tails connected together. The current in a parallel circuit breaks up, with some flowing along each parallel branch and re-combining when the branches meet again. The voltage across each resistor in parallel is the same.

Analysis of our measurements should enable us to derive relationships between total resistance - RT, total current - IT, and the individual voltage drops across and currents through each

resistor.

Material Required:

DC Power Supply 1k resistors 10k resistor Multimeters

Procedure:

A. Series CircuitsConstruct the circuit shown below. "A", "B", "C" and "R" are labels for various points in the circuit. "R" is the common reference point - in this circuit, it is the negative end of the power supply.

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Measure:

TOTAL CURRENT IT = __________

CURRENT THROUGH R1 I1 = _______



VOLTAGE ACROSS R1 VR1 = _______



Calculate the total resistance RT=

V TIT

=12VIT

=

1. How does IT compare with the individual currents I1, I2 and I3?

2. Determine the relationship between the supply voltage VT and the individual voltage drops VR1, VR2 and VR3.

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3. Determine the relationship between RT and the individual resistances R1, R2 and R3.Measure:

VOLTAGE FROM POINT A TO REFERENCE VA = ______

VOLTAGE FROM POINT B TO REFERENCE VB = ______

VOLTAGE FROM POINT C TO REFERENCE VC = ______

VOLTAGE FROM “POINT A” TO POINT C” VAC = ______

VOLTAGE FROM “POINT C” TO POINT A” VCA = ______

VOLTAGE FROM “POINT R” TO POINT B” VRB = ______

VOLTAGE FROM “POINT R” TO POINT A” VRA = ______

*Note: By convention, place the + lead at the first point and the - lead at the second point.

Looking at your measurements, could you have predicted them from your values for the supply voltage VT and the individual voltage drops VR1, VR2 and VR3? How?

B. Parallel CircuitsConstruct the circuit shown below:

Measure:

TOTAL CURRENT IT = _______




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V TIT

=12VIT

=

4. How does IT compare with the individual currents I1 and I2?

5. Determine the relationship between the supply voltage VT and the individual voltage

drops VR1 and VR2.

6. Determine the relationship between RT and the individual resistances R1 and R2.

Replace R2 with a 10k resistor and repeat the following measurements.

Measure:

TOTAL CURRENT IT = _____






V TIT

=12VIT

=

7. Do the relationships expressed in questions 4, 5 and 6 still hold true for this circuit? If not, can you determine a relationship that will hold true for both circuits?

8. In a parallel branch of two resistors, the resistor with the larger resistance will have [a larger / the same / a smaller] current. CIRCLE THE CORRECT ANSWER.

9. In a parallel branch of two resistors, the resistor with the larger resistance will have [a larger / the same / a smaller] voltage drop. CIRCLE THE CORRECT ANSWER

C. Series – Parallel Combinations

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In actual practice, you’ll rarely come across a circuit comprised solely of series or parallel resistors. Usually, you’ll find a combination of the two forms as illustrated in the following example.

Construct the circuit shown below:

Based on what you learned in part A and part B of the experiment, you should be able to analyze this electric circuit.

MEASURED VALUES:

VT = ____________ IT = ____________

V1 = ____________ I1 = ____________

V2 = ____________ I2 = ____________

V3 = ____________ I3 = ____________

V4 = ____________ I4 = ____________

V5 = ____________ I5 = ____________

RT=V TIT

=

*Hint to determine calculated values: Using what you know about series and parallel circuits, determine the total equivalent resistance of the circuit first.

CALCULATED VALUES:

RT = ____________

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VT = ____________ IT = ____________

V1 = ____________ I1 = ____________

V2 = ____________ I2 = ____________

V3 = ____________ I3 = ____________

V4 = ____________ I4 = ____________

V5 = ____________ I5 = ____________

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EXPERIMENT 5- Kirchhoff’s Laws

Objective:-Utilizing of Kirchhoff’s current and voltage Law.

Brief theory:

The first law, known as Kirchhoff’s current Law (or KCL), states that the current flows uniformly in a circuit. Electrons do not bunch up. At any node the sum of the current flowing in to the node is exactly equal to the sum of the currents flowing out of the node.

The second law, Known as Kirchhoff’s Voltage Law (KVL), states that the sum of the voltage in a closed loop is always equal to zero.

This experiment provides an opportunity to utilize Kirchhoff’s Voltage Law and Kirchhoff’s Current Law as tools to analyze more complex circuits.

Material required:

DC Power Supply 1k resistors 2k resistor Multimeters

Procedure:

Build the following circuit:

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1. Calculate the current flowing through each resistor. Support your work. Be sure to show the directions of the currents used in your equations on the circuit diagram above.

Current through R1 I1 = _______


Current through R3 I3 = ______

2. Measure:




3. Determine a new value for B1 so that the voltage across R1 is equal to zero (B2 = 10V).

4. Test your solution.

5. Determine a new value for B2 so that the voltage across R1 is equal to zero (B1 = 5V).

6. Test your solution.

7. Is there any possible, non-trivial (i.e. B1 = 0 and B2 = 0) combination for B1 and B2 that will cause the voltage across R3 to be zero? Test any possible solution.

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Experiment 6- Speed and Acceleration.

Objective:-To measure the time intervals, speed and acceleration of the moving object.

Brief theory:-Speed (s symbol) is the distance traveled (d) divide by time taken (Δt) for the journey. Distance and Time scalar quantity and therefore speed will also be scalar quantity .speed is calculated as follows.

speed (¿ ms )=distance (¿m )time (¿s )

s=dΔ t Where, m=meter; S=second

Acceleration (symbol a) the rate of change of velocity. It is the measure of how fast the velocity of an object changes in time. If we have a change of velocity(Δv) over in a time interval(Δt) then acceleration(a) is defined as

acceleration(¿ms2 )=change∈velocity (¿ ms )change∈time (¿ s )

a=ΔvΔt

Since velocity is vector ,acceleration is also vector.

Material required.

Smart digital timer

Photo gate 1 and 2.

Movable Object like trolley, toy car. etc

Procedure to operate the timer

1) Connect the photo gates with the instrument (inclined plane, dynamic track, linear track etc)t o take the results of trolley moving on these instrument.

2) Connect both stereo plugs photo gate s to the timer via. Stereo sockets fitted on the front of timer.

3) Connect the main lead of the timer to the main socket 230V 50 Hz AC.

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4) Switch ON the illuminated rocker switch fitted on the front panel of the timer.5) Then it will show you the AGA Group to indicate that the front panel of the timer.6) Press the select button, Then it will show the DISTANCE=0000mm.7) Press the DISTANCE button to the set the distance inside the timer the timer as the

distance in between the two photo gates.8) Now press the select button again, Then it will show TIME=0.00s.9) Now pass out the object from the photo gate 1 as the object will cross the photo gate

the timer will get start and it will get stop as the object cross the second timer.10) Press the select button the timer will show the speed of the object again press the same

button then timer will show the acceleration of the object.11) To store the memory simply press the memory button and wait for 2 second.12) To see the results press the result button. The result will show on the timer.13) For more results press the select button and set the distance for the next result and

repeat above procedure again.

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Experiment 7- Electromagnets

Objective:- Creating a magnet using electricity.

Brief theory:-

An electromagnet is a magnet that runs on electricity. Unlike a permanent magnet, the strength of an electromagnet can easily be changed by changing the amount of electric current that flows through it. The poles of an electromagnet can even be reversed by reversing the flow of electricity.

An electromagnet works because an electric current produces a magnetic field. The magnetic field produced by electric current forms circles around the electric current.

It provides an opportunity to see how electrical current flowing through a coil creates an electromagnetic field, which is transferred to the nail. Whenever there is current flow, there is also heat generated by the resistance of the wire. If there is more current flowing, then more heat will be generated. If there is too much current, the heat could melt the wire and cause a burn injury.

Material required

Insulated copper Thin wire around 15cm Long nail (1) AA size 1.5v Batter (2) Paper clip (10)

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Procedure

1. Wrap the wire that has been stripped bare very tightly around the nail - at least 20 times. Cut the wire leaving a few inches of wire at each end.

2. Tape down the end of the wire from the top of the nail to the negative pole of the battery. Make sure the wire is touching the battery end.

3. Open the knife switch and connect the wire from the bottom end of the nail to the terminal on the knife switch.

4. Cut another short piece of wire and tape the wire to the positive pole of the battery.5. Connect the wire from the battery to other terminals on the knife switch.6. Close the circuit by closing the knife switch. When you do that, you create a circuit of

electricity that passes through the wire round around the nail.7. Touch the point of the nail to a couple of paper clips and watch what happens.

NOTE: Making an electromagnet uses up the battery somewhat quickly which is why the battery may get warm, so disconnect the wires when you are done exploring.

Questions

1. The more turns of wire your magnet has, the better…………………………………………………….2. The more current that passes through the wire, the better………………………………………….3. List material that picked up by electromagnets?

4. Does the thickness or length of the nail affect the electromagnets strength?

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5. Does the thickness of the wire affect the power of the electromagnet?

Experiment 8-Magnetism

Objective:-to investigate magnetic line of force and induction.

Brief theory:-

I. Magnetism …… Line of force …………….II. Magnetics ……. Magnetic Induction ………

I. "Lines of Force"

Material required

A sheet of paper

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A magnet

Steel filings (these can be made by taking a steel wool pad and pulling it apart until you get a small pile of tiny pieces of steel)

Procedure

1. Set the magnet on the table2. Cover the magnet with a piece of paper3. Sprinkle the steel filings over the paper

Result

The filings will take the shape of a "figure eight ", which is the lines of force of the magnetic field

Why

The filings will line up along the lines of magnetic force which are close together at the poles of the magnet and farther apart as you move away from the poles.

Questions

Use different sizes and shapes of magnets see the difference?

II. "Magnetic Induction"

Material required

Magnet Several paper clips

Procedure

1. Hang one paperclip from the magnet.2. Use the hanging clip to pick up other paper clips.

Result

See how many paper clips you can pick up using only one magnet.

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Why

The magnet's lines of force are transmitted through the first paperclip to the second one by induction.

Questions

Use different sizes of paper clips and see the difference.

What will happen when paper clips have plastic coating?

Experiment 9-Computer simulation

Objective:- To investigate the connection between current, voltage and resistance of a fixed resistor using computer simulation.

Brief Theory:

All materials (except superconductors) resist the flow of electric current to some extent. Good conductors of electricity (eg. copper, aluminium and gold) are not strong resistors. The coiled wires in electric radiators and kettles have much more resistance. Energy has to be used to force electrons through the wire. This conversion of electrical energy into heat energy causes the temperature of the wire to increase.

Resistors are often used in electronic circuits to reduce the current. In radio and TV circuits, resistors keep currents and voltages at the levels needed to make other parts work properly.

A formal report is not required for this practical exercise. You are to use Crocodile Clips to construct a circuit, answer questions, tabulate measurements and use Excel to produce a graph. Staple the completed instruction sheet to a printout containing the circuit and the line graph. Make sure all sections are fully labelled, and your name is on both sheets.

Procedure.

The Circuit

1. Create a circuit with a battery, a light globe, a resistor, a switch and an ammeter in series. Add a voltmeter across the resistor.

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2. Change the battery voltage (emf) from 9V to 10V by clicking on the number above the symbol and completing the resulting table as shown below left.

3. Change the resistance from 10k (10000) to 100 by clicking on the number above the symbol and completing the resulting table as shown below right.

4. Label this circuit: Resistor Circuit by opening the Add menu and choosing Text. Type your label then drag it into place. Double click to alter the text.

5. Open word spreadsheet and set up a table to record the following measurements:

Battery Voltage

(volts)

Resistance

R (ohms)

Current Through Resistor

I (amps)= D3

Voltage across Resistor

V (volts) =D4

VI

10

8

6

4

2

6. Copy your circuit [Edit Copy Design] then paste it beside your Excel table. [First remove the tick beside the Copy with Green Fill choice in the Options menu

of Crocodile Clips if you do not want the green fill in ammeters and voltmeters].7. Note: the voltmeter and ammeter automatically change units at times so make sure you

convert all measurements back to volts and amps before recording V and I in the table.

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HINT: Divide by 1000 (move decimal point 3 places to the left)

to change mA to A (or to change mV to V).

eg. 96.8 mA should be recorded as 0.0968 A but 1.96 V should not be changed

8. What current would you expect to flow through the resistor when V = 0 volts? ………. Add this to your table.

9. Use a formula of the type: = D4/D3 to complete the last column.10. Use word to graph V against I (V on the vertical scale, I on the horizontal).

Make sure you correctly label both axes and include a heading (eg. V-I Characteristics of a Resistor).

Conclusions:

Two facts about V/I are apparent from the table and graph:

…………………………………………………………………………………………

…………………………………………………………………………………………

Resistance (R), Voltage (V) and current (I) are connected by this rule:

R =

This rule is called Ohm’s Law when it is rewritten in the form V =

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