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  • 7/31/2019 SAC 4 - Folio of Electronics Practical Activities

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    VCE Unit 3: SAC 4 Outcome 3.2

    1

    SAC 4 Annotated Folio of Practical Activities for Electronics

    Outcome 2

    NAME ___________________________ ID ____________ Score _____ / 20

    Conditions for the task

    You will complete three practical activities:

    Ohmic and Non-Ohmic Resistors in Series and Parallel

    You will work in pairs or small group to collect the results in 9.05

    You will work individually to analyse your results and write your evaluation and

    conclusion in 5.04

    Date: 7 May 2012

    Investigation of Diodes

    You will work in pairs or small group to collect the results for Parts A & B in 9.05

    You will work individually to complete Part C in 5.04

    You will work individually to analyse your results and write your conclusion in 5.04

    Date: 14 May 2012

    The Amplifier Simulation Investigation

    You will work individually to complete the investigation in 5.04

    You will work individually to write your conclusion in 5.04

    Date: 21 May 2012

    You must record all results individually in this Booklet.

    The teacher will collect the Booklet on completion of each activity.

    All work will be completed in class time.

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    Ohmic & Non-Ohmic Resistors in Series and Parallel Circuits

    AIM:

    To measure current and voltage for an Ohmic and Non-Ohmic resistor individually and when

    combined in series and parallel.

    To recognise how Current vs Voltage graphs differ for Ohmic and Non-Ohmic resistors To use Raw Data and Excel to find the relationship between current and voltage for the

    Ohmic and Non-Ohmic resistor.

    To compare the actual relationship between current and voltage measured by experiment for

    series and parallel circuits with the relationship predicted by theory from Processed Data.

    THEORY:

    Symbols: Voltage V Current I

    Resistance R = V/I, Ohmic Resistance Ro (constant), Non-Ohmic Resistance Rn(changes

    with current)

    Resistance of Ro and Rn in series Rs Resistance of Ro and Rn in parallel R//

    For an Ohmic resistor a graph of Voltage, V vs Current, I is a straight line through the origin

    with gradient equal to the constant resistance, R.

    A light globe is a Non-Ohmic resistor whose resistance increases with current.

    Resistors combined in Series and Parallel

    APPARATUS:

    DC power supply, 15 resistor (Ohmic resistor), rheostat (variable resistor), 12 V 36 W light bulb

    (Non-Ohmic resistor), ammeter, voltmeter, connecting wires.

    METHOD:

    Four different loads will be placed in the circuit shown:

    Load 1. Ro = 15 , Ohmic resistor

    Load 2. Rn = Light Globe, Non-Ohmic

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    Load 3. Rs = Ro in series with Rn (Ohmic and Non-Ohmic resistors in series)

    Load 4. R// = Ro in parallel with Rn (Ohmic and Non-Ohmic resistors in parallel)

    1. Connect the power supply, rheostat, ammeter, voltmeter and Load 1 as shown in the circuitdiagram.

    To avoid damaging the multimeters, use their largest scales initially then change to the relevant

    scale.2. Adjust the rheostat to vary the voltage across the load and record 10 widely spaced values of

    voltage and corresponding current in the Raw Data Table.

    Note: the light bulb will not glow for low currents

    3. Repeat 1. 3. for Loads 2, 3 and 4

    Raw Data Table

    Ohmic/Non-Ohmic Circuits

    Ohmic Non-Ohmic Series (Actual) Parallel (Actual)

    V(V) I (A) V(V) I (A) V(V) I (A) V(V) I (A)

    Analysis4. Copy your data from the Data Table into Excel

    5. Plot a Scatter Plot of Current vs Voltage for the Ohmic and Non-Ohmic resistances on the one setof axes.

    For the Ohmic resistor insert a linear trend line through the origin and show the equationusing correct symbols and significant figures

    Write the equation here:

    Equation 1: I = ____V For the Non- Ohmic resistor insert a power trend line and show the equation using correct

    symbols and significant figures

    Write the equation here:

    Equation 2: I = ____V____

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    VCE Unit 3: SAC 4 Outcome 3.2

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    6. Plot a ScatterPlot of Voltage vs Current for the Ohmic and Non-Ohmic resistances on the one setof axes.

    For the Ohmic resistor insert a linear trend line through the origin and show the equationusing correct symbols and significant figures

    Write the equation here:

    Equation 3: V = ______ I What value does this equation predict fro Ro?

    Ro = _____ For the Non- Ohmic resistor insert a power trend line and show the equation using correct

    symbols and significant figures

    Write the equation here:

    Equation 4: V = ____I____

    7. Complete the Processed Data Table in Excel. Use: Equation 3 to complete Column 2 Equation 4 to complete Column 3 Equation 1 to complete Column 6 Equation 2 to complete Column 7

    Processed Data Table

    Series (Predicted) Parallel (Predicted)

    I (A) Vo Vn Vs = Vo + Vn (V) V (V) Io In I// = Io + In (A)

    0.02 1.00

    0.04 2.00

    0.06 3.00

    0.08 4.00

    0.10 5.00

    0.12 6.00

    0.14 7.00

    0.16 8.00

    0.18 9.00

    0.20

    10.0

    0

    8. Complete Columns 4 and 8.

    9. Plot on the one set of axes, a Scatter Plot of Current vs Voltage for Series (Actual) from the RawData Table and Series (Predicted) from the Processed Data Table.

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    10.Plot on the one set of axes, a Scatter Plot of Current vs Voltage for Parallel (Actual) from theRaw Data Table and Parallel (Predicted) from the Processed Data Table.

    Conclusion and EvaluationA statement of how Ohmic and Non-Ohmic resistors differ and how the graphs plotted in points 9. and 10.

    support the theory for resistors in series and parallel.Was the experiment successful? How could it be improved? What are the sources of error?

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    VCE Unit 3: SAC 4 Outcome 3.2

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    Investigation of DIODES

    AIM:

    1. To measure the forward and reverse resistance of diodes

    2. To use Excel to plot the current-voltage characteristics of a diode

    3. To use simulations to look at diode operation and rectification.

    Theory:

    A diode allows an electric current to flow in one direction, but blocks it in the opposite direction.

    Circuits that require current flow in only one direction only include one or more diodes.

    Diodes are based on semiconductor p-n junctions. In a p-n diode, conventional current can flow from

    the p-type side (the positive anode) to the n-type side (the negative cathode), but not in the

    opposite direction.

    The voltage drop across a normal silicon diode at rated currents when forward biased is 0.6 to 0.7

    volts. This value is the diode turn-on voltage. For other diode types it has a different value. eg light-

    emitting diodes (LEDs) can be 1.4 V or more.

    A typical graph of Current vs Voltage for a diode is

    shown.

    Equipment:

    DC Power Supply

    2 Digital Multimeters

    Board with1k resistor and diode

    Rheostat

    Leads

    METHOD and DATA COLLECTION:

    Part A: The Multimeter and Diode Polarity

    1. Multimeter:

    a. Connect the red lead to the V. .mA jack and the black lead to the COM jack.

    b. The multimeter can measure voltage when connected in parallel with the circuit

    element and with the rotary switch set to the left voltage band. Start with the

    range at the highest range position and then reduce by turning the dial anti-

    clockwise.

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    c. The multimeter can measure current when connected in series with the circuit

    element and with the rotary switch set to the right current band.

    Start with the range at the highest range position and then reduce by turning the

    dial clockwise.

    2. Diode Operating Voltage:

    a. Use a multimeter to measure the voltage of the diode. Turn the multimeter dialto the special diode setting.

    Connect the black negative lead to the bar end of the diode and the positive red

    lead to the other end of the diode. The diode voltage for forward biased is

    shown.

    Vdiode = ____________V

    b. Next reverse the polarity of the multimeter leads so that the positive lead is now

    connected to the bar end. The diode is now reverse biased.

    The reading should show 1 indicating that current does not flow in the reverse

    direction.

    c. Compare the forward and reverse voltages. Explain how this will affect current

    flow in a circuit.

    Part B: Diode Current-Voltage Characteristics

    1. To examine how the current through a diode varies as the potential difference across it is

    changed, connect the circuit as shown below with the diode forward biased.a. 1st connect the power supply to the rheostat using the 2 connections at the base.

    b. Next connect the lead from the 1000 to the top connection.

    c. Finally insert the 2 multimeters to measure the current and voltage for the diode.

    1000 ohm

    VR

    Vsupply

    1 k

    2. Vary the rheostat setting so that the potential difference, Vdiode across the diode from 0.0

    Volts to the maximum possible. For each setting, record the voltage and current I in the

    table below.

    3. Also record the uncertainty in voltage and current in the table heading by observing anyfluctuations of the meter.

    12V

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    Raw Data Table

    Forward biased

    Vdiode (Volts)

    Vdiode =

    I (milliamps)

    I =

    Vdiode (Volts)

    Vdiode =

    I (milliamps)

    I =

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    ANALYSIS:

    4. Enter your results into an Excel Spreadsheet and create a Scatterplot of Current (mA) vs

    Vdiode (Volts).

    a. Your Scatterplot must show a Exponetial trendline with the Equation.

    b. Show x and y error bars.

    c. Use all the correct conventions.5. How does the maximum value you found for Vdiode compare with the value of Vdiode found

    using the multi-meter?

    6. How do values you found for Vdiode by the 2 methods compare with the expected range of

    0.6 0.7?

    Part C: Simulation

    1. Diode:

    a. Go to http://www.falstad.com/circuit/e-diodevar.htmland complete the following

    Table.

    b. Go to:http://www.falstad.com/circuit/e-diodecurve.htmland observe the Current

    vs Voltage across the diode for a time varying input signal.

    c. Half-wave rectifier - Go to :http://www.falstad.com/circuit/e-rectify.html

    i. Sketch the circuit.

    ii. What is the input Voltage from the ac power supply? = _____ V

    iii. What is the voltage across this diode? Vdiode = _______ V

    Vdiode (Volt) 0 0.2 0.3 0.4 0.5 0.6 0.62 0.64 0.66 0.68 0.70 0.72

    I

    (indicate if pA, A

    or mA)

    http://www.falstad.com/circuit/e-diodevar.htmlhttp://www.falstad.com/circuit/e-diodevar.htmlhttp://www.falstad.com/circuit/e-diodecurve.htmlhttp://www.falstad.com/circuit/e-diodecurve.htmlhttp://www.falstad.com/circuit/e-diodecurve.htmlhttp://www.falstad.com/circuit/e-rectify.htmlhttp://www.falstad.com/circuit/e-rectify.htmlhttp://www.falstad.com/circuit/e-rectify.htmlhttp://www.falstad.com/circuit/e-rectify.htmlhttp://www.falstad.com/circuit/e-diodecurve.htmlhttp://www.falstad.com/circuit/e-diodevar.html
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    iv. On the axes below sketch the input signal (green) from the power supply

    and the output signal (yellow) across the 640 resistor. Annotate your

    graph to indicate if current is flowing or not at different times.

    CONCLUSION:Summarise what you have learnt about the diode. Use the words forward bias, reverse bias and diode turn-on

    voltage. State and compare the diode turn-on voltages you measured.

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    The Amplifier Simulation

    Applet:http://ngsir.netfirms.com/englishhtm/Amplifier.htm

    1) Open the Applet and use the default values for all variables unless told otherwise. You canreturn to the default settings by refreshing..

    2) What is the voltage gain of the amplifier?

    AV =

    3) This is an inverting amplifier. What does that mean?

    4) With an input signal with vin = 0.4 V (input amplitude = 0.2 V), what is vout?(nb: means from peak to peak and we use lower case v for ac signals and upper case V for dc

    signals)

    vout =V

    5) Increase the input signal to vin = 0.8 V (input amplitude = 0.4 V).a) What is vout?

    vout = 8 V

    b) Describe and sketch the output signal.

    6) Refresh and make RC = 1.8 k

    7) What is the voltage gain of the amplifier?

    AV =

    8) With an input signal with vin = 0.4 V, what is vout?

    vout = V

    9) With an input signal with vin = 0.8 V.a) What is vout?

    vout = V

    http://ngsir.netfirms.com/englishhtm/Amplifier.htmhttp://ngsir.netfirms.com/englishhtm/Amplifier.htmhttp://ngsir.netfirms.com/englishhtm/Amplifier.htmhttp://ngsir.netfirms.com/englishhtm/Amplifier.htm
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    VCE Unit 3: SAC 4 Outcome 3.2

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    b) Describe and sketch the output signal.

    10)Refresh and make R1:R2 = 6

    11)With an input signal with vin = 0.4 V, what is vout?

    vout = V

    12)Increase the input signal to vin = 1.0 V.a) What is vout?

    vout = V

    b) Describe and sketch the output signal.

    Conclusion:Summarise what you have learnt about amplifiers. Use the words voltage gain, inverting amplifier,

    distortion and clipping in your answer.

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    Assessment Sheet: SAC 4 Annotated Folio of Practical Activities for

    Electronics

    Name: _________________________ ID _____________ Score _______ /20

    Comments:

    Criterion Excellent (5) Good (4) OK (3) Poor/Bad

    Raw & Processed

    DataA record of your

    observations and

    measurements and values

    determined from the raw

    data

    Sufficient raw data has been collected.

    Data or observations are presented in

    well organised, correct ruled or

    computer generated tables.

    Data has been correctly processed when

    required

    Correct units and significant figures are

    given.

    Calculated values are presented.

    Error are recorded (when applicable)

    One or twoitems required

    for excellent

    are missing.

    About half ofthe items

    required for

    excellent

    have been

    completed

    Most of the itemsrequired for

    excellent are missing.

    2

    Data that of anotherstudent and this is

    acknowledged

    1

    No data recorded or

    data that of another

    student and this is

    not acknowledged

    0

    AnalysisManipulations of data to

    get what you are after;

    include graphs in this

    section. Show sample of

    each type of calculation.

    Include calculations of

    absolute or relative error if

    required.

    Correct graphs are presented. Graphs are used correctly to obtain

    required information

    All applicable formulas are listed.

    All symbols are defined.

    A sample of each type of calculation is

    shown.

    Setting out is neat, correct and easy to

    follow.

    All calculated values are clearly

    identified with units

    Analysis shows understanding

    One or twoitems required

    for excellent

    are missing.

    About half ofthe items

    required for

    excellent

    have been

    completed

    Most of the itemsrequired for

    excellent are missing.

    2

    Calculations identical

    to those of another

    student

    1

    No calculationsshown

    0

    QuestionsAnswer all questions

    included on your instruction

    sheet.

    All questions have been answered

    All answers are correct

    Answers are in clear English and/or are

    illustrated with a clear diagram. Answered are neatly presented.

    Answers show understanding

    One or the

    items required

    for excellent is

    missing.

    Two of the

    items

    required for

    excellent aremissing.

    Most of the items

    required for

    excellent are missing.

    2 Answers identical to

    those of another

    student

    1

    Questions are notanswered

    0

    Conclusion &

    EvaluationThis is a briefsummary of

    your results and conclusions

    drawn from them.

    State any equations you

    found.

    State any values you

    calculated (with uncertainty

    if applicable).

    State the percentage

    difference from the

    expected value if possible.

    How could the experiment

    be improved?

    A brief summary of results is given.

    Equations and values determined from

    the results are given.

    An objective, scientific conclusion

    relating theory to the results, using

    proper scientific language, is given.

    Sources of error are identified Suggestions for improving the

    experiment are given.

    Mistakes are acknowledged.

    One or the

    items required

    for excellent is

    missing.

    Two of the

    items

    required for

    excellent are

    missing.

    Most of the items

    required for

    excellent are missing.

    2

    Conclusion identicalto that of another

    student1

    No conclusion given

    0