ADISS ABABA SCIENCE TECHNOLOGY ENGINEERING AND MATHEMATICS CENTER

Electronics Laboratory Manual Curriculum

Grade 9 and 10

2012

Compiled By:-ANTENEH FISSEHA

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 / 3
Electrostatics /
  1. Electric charge
  2. Electric force and field
  3. Electroscope
  4. Electric potential
  5. Capacitor and capacitance.
/ 3
Current Electricity /
  1. Law and Kind of Circuits
Electric circuit
Electric current
Ohms law
Kerchiefs current law
Kerchiefs voltage Law
Series circuit
Parallel Circuit / 3
Introduction to Electronics /
  • Conductor, insulator and semiconductors
/ 1
  • Components demonstration
Inductor
Integrated Circuits(IC’s)
Diode
LED
LDR
Transistor / 2
Electromagnetism /
  1. Magnet
Types of magnet
Poles of magnet
Properties of magnet / 2
  1. Lines of force of magnet
Compass
Properties of lines of force of magnet / 2
  1. Electromagnetic induction
/ 1
  1. Motor effect
Constructing simple motor / 2
  1. 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.

Objective:- Using Digital Multimeter

Brife Therory:-

  1. Using digital voltmeters
  2. Using digital ammeters
  3. Using digital ohmmeters
  4. 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.

Where:-

  1. Selection knob what Variables to be measured
  2. Range selection
  3. 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.

  1. If the polarity error not connected properly, it indicates a negative sign (-) on the display screen, you should change the position of the leads.
  2. To measure the voltage across the resistance, we must connect the voltmeter parallel to the resistance as shown below.

Fig.2b. Voltage measured across the resistance.

  1. 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.

  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.

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

Brief theory:-

Theelectronic color codeis used to indicate the values or ratings of electronic components, very commonly forresistors, but also forcapacitors,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

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

  • bandAis first significant figure of component value (left side)
  • bandBis the second significant figure
  • bandCis the decimal multiplier
  • bandDif present, indicates tolerance of value in percent (no band means 20%)

For example, a resistor with bands ofyellow, violet, red, and goldwill have first digit 4 (yellow in table below), second digit 7 (violet), followed by 2 (red) zeros: 4,700ohms. 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

Objective:-Verifying electrostatics Effect.

BriefTheory:-

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. Inelectrostatics we therefore often work with charge in microcoulombs (1μC=1x10-6C)and nanocoulombs (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 balloonand rub it with piece of silk or hair. Just bring rubber balloon close to Electroscope Holdit 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 otheri.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.

  1. Take a inflated rubber balloon and close contact to a piece of rough paperi.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

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.

Voltage,v (V) / Theoretical Ampere,I(A) / Practical Ampere,I(A)
1.5
3
4.5
6
7.5
9

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?

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:

  1. Series Circuits

Construct 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.

Measure:

TOTAL CURRENT IT = ______

CURRENT THROUGH R1 I1 = ______

CURRENT THROUGH R2 I2 = ______

CURRENT THROUGH R3I3 = ______

VOLTAGE ACROSS R1VR1 = ______

VOLTAGE ACROSS R2VR2 = ______

VOLTAGE ACROSS R3 VR3= ______

Calculate the total resistance

  1. How does IT compare with the individual currents I1, I2 and I3?
  1. Determine the relationship between the supply voltage VT and the individual voltage drops VR1, VR2 and VR3.
  2. 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?

  1. Parallel Circuits

Construct the circuit shown below:

Measure:

TOTAL CURRENT IT = ______

VOLTAGE ACROSS R1VR1 = ______

VOLTAGE ACROSS R2VR2= ______

CURRENT THROUGH R1I1 = ______

CURRENT THROUGH R2 I2 = ______

Calculate the total resistance

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 = _____

VOLTAGE ACROSS R1VR1 = ______

VOLTAGE ACROSS R2VR2= ______

CURRENT THROUGH R1I1 = ______

CURRENT THROUGH R2 I2 = ______

Calculate the total resistance

  1. 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?
  1. 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.
  1. 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

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 = ______

*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 = ______

VT = ______IT = ______

V1 = ______I1 = ______

V2 = ______I2 = ______

V3 = ______I3 = ______

V4 = ______I4 = ______

V5 = ______I5 = ______

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:

  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 R1I1 = ______

Current through R2I2 = ______

Current through R3I3 = ______

  1. Measure:

Current through R1I1 = ______

Current through R2I2 = ______

Current through R3I3 = ______

  1. Determine a new value for B1 so that the voltage across R1 is equal to zero (B2 = 10V).
  2. Test your solution.
  3. Determine a new value for B2 so that the voltage across R1 is equal to zero (B1 = 5V).
  4. Test your solution.
  5. 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.

Experiment6- 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.

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

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.

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.

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)