Revision as of 22:52, 2 December 2010

Forest_Electronic_Instrumentation_and_Measurement

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 [[Forest_Electronic_Instrumentation_and_Measurement]]
-= Lab 1=
+= [[TF_Lab1_Writeup]]=
-=Kirchoff's Law (50 pnts)=
-== Smokey Circuits==
-When doing these labs it is important to determine the limitations of your electrical components in order to avoid damaging them.
-This lab uses resistors.  Resistors are vulnerable to melting if you push too much current through them.
-Resistors have power ratings ranging from 1/8 Watt up to several Watts.  The common resistors are rated at 1/4 Watt.  Let's assume this rating for the resistors in this lab.
-Determine the maximum voltage of the DC power supply you will use. (ie, 30 Volts)
-;<math> P =I^2R = V^2/R \Rightarrow R = \frac{V^2}{P} > \frac{\left (30 V \right)^2}{1/4 \mbox{Watt}} > 3600 \Omega</math>
-:By keeping your resistance values above 3600 <math>\Omega</math> you should be able to avoid burning up 1/4 Watt resistors when your max voltage is 30 Volts.
-The next objective is to use resistors which allow currents that you can measure with your voltmeter.
-;Since <math>V=IR \Rightarrow I = V/R = 30 \mbox{Volts}/3600 \Omega = 8\mbox{mA}</math>
-Determine the range of currents which the voltmeter can measure. (ie 1 mA)
-To get measurable currents you need low resistance BUT the lower resistances will need to have a high power rating.  These two competing properties limit the range of resistances you can use.
-Select the three resistors you should use for this experiment.
-==Construct the circuit below==
-[[File:TF_EIM_Lab1.png | 400 px]]
-==Enter the values of the DC voltage and Resisters that you used.==
-Use a voltmeter to measure the potential difference and resistances.
-{| border="3"  cellpadding="20" cellspacing="0"
-|Variable ||Measured Value
-|-
-| <math>V_A </math> ||
-|-
-| <math>R_1</math> ||
-|-
-| <math>R_2</math> ||
-|-
-| <math>R_3</math> ||
-|}
-==Enter the measured and predicted quantities in the table below==
-Given <math>V_A</math> and the values of all resistors, use Kirchoff's laws to predict
-a.) Predict the value of <math>V_B</math>
-b.) Predict the values of the three currents.
-c.) compare your predictions and measurements  by filling in the table below.
-{| border="3"  cellpadding="20" cellspacing="0"
-|Variable ||Measured Value|| Predicted Value|| % Difference
-|-
-| <math>V_B</math> ||  || ||
-|-
-| <math>I_1</math> ||  || ||
-|-
-| <math>I_2</math> ||   || ||
-|-
-| <math>I_3</math> ||   || ||
-|}
-= Internal resistance (30 pnts)=
-Measure the internal resistance of your power source by graphing the potential difference on the x-axis and the current on the y-axis for several values of the resistance <math>R_L</math> shown in the circuit below.  Begin with <math>R_L = 1k\Omega</math> and then decrease it by a factor of 5 for each subsequent measurement.  You can use a volt meter to measure the current and potential difference.
-=Questions (20 pnts)=
-#What conservation law is involved in Kirchoff's Loop Theorem?
-#What does the slope in the internal resistance plot above represent?

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