Experiment 6: Electrical Circuits In this experiment, we will construct series and parallel circuits of resistors and investigate their properties

Experiment 6: Electrical Circuits

In this experiment, we will construct series and parallel circuits of resistors and investigate their properties. We will measure values of current and voltage and check the basic rules relating to the voltage and current distributions in these circuits and the total resistance of the circuit

Series Circuit

The total voltage is equal to the sum of the individual voltages across each resistor.

Vtotal= V1+V2+V3

The currents through each resistor are the same and equal to the total current

Itotal= I1=I2=I3

The total resistance is equal to the sum of the individual resistances

Rtotal= R1+R2+R3

Parallel Circuit

Voltage across each resistor is the same and equal to the total voltage

Vtotal= V1=V2=V3

The total current is equal to the sum of the currents through each resistor

Itotal= I1+I2+I3

The total resistance can be found as

1Rtotal= 1R1+1R2+1R3

Procedure

Physics Simulations: Circuit Construction Kit: DC - Virtual Lab

https://phet.colorado.edu/sims/html/circuit-construction-kit-dc-virtual-lab/latest/circuit-construction-kit-dc-virtual-lab_en.html

Preliminary

To measure the voltage, use the voltmeter like shown in the picture below

To measure the current, use the ammeters. Break the circuit and place the ammeter to close the circuit again as shown in the picture below

Part A: Series Circuit

Construct a Series circuit as illustrated on the circuit diagram below with 10-volt battery and three resistors with arbitrary but different values of resistance.

Measuring Voltages

1. Use voltmeter to measure the voltages across individual resistors (V₁ , V₂ , V₃) and the voltages across the R₁&R₂ combination (V_BE), across the R₂&R₃ combination (V_DG), and the total voltage across the R₁&R₂&R₃ combination (V_BG). Enter your data into the Data Table A

Data Table A

R1= _________________	V1= _________________	VBE= _________________
R2= _________________	V2= _________________	VDG= _________________
R3= _________________	V3= _________________	VBG= _________________

2. Calculate voltages across the combinations (V_BE , V_BE , V_BE) using the voltage rule for series connection and compare the results with the experimental values in the table below

Measuring Currents

1. Use ammeter to measure the currents between points A and B (I_AB), between points C and D (I_CD), between points E and F (I_EF), and between points G and H (I_GH).

          IAB=

________          ICD=

________           IEF=

________          IGH=

________    

2. Make sure that IAB=ICD=IBF=IGH=Itotal

   

   .

Measuring Resistances

1. Find the total resistance Rtotal

   

    using Ohm’s law and the measured values of the total voltage (Vtotal=VBG

   

   ) and total current Itotal

   

    .
2. Calculate the total resistance Rtotal

   

    using the series rule for resistances and the values of R1,R2,and R3

   

   .
3. Compare the measured and calculated values of Rtotal

   

    in the following table

	Measured	Calculated	% Error
Rtotal

Questions

1. For series connection is the total voltage larger, the same or smaller than the voltage across any individual resistor?

2. For series connection is the total current larger, the same or smaller than the current through any individual resistor?

3. For series connection is the total resistance larger, the same or smaller than the resistance of any individual resistor?

Part B: Parallel Circuit

Construct a Parallel circuit as illustrated on the circuit diagram below with 10-volt battery and the same three resistors you used in Part A.

Measuring Voltages

1. Use voltmeter to measure voltages across resistor R1

   

    (V1

   

   ), across resistor R2

   

    (V2

   

   ), across resistor R3

   

    (V3

   

   ), and the total voltage (Vtotal

   

   ).

          V1=

________          V2=

________           V3=

________          Vtotal=

________    

2. Make sure that V1=V2=V3=Vtotal

   

   .

Measuring Currents

3. Measure the currents through individual resistors (I1,I2,I3

   

   ) by inserting ammeter between points C and D, E and F, G and H, respectively. Measure the total current between points A and B (I_AB) and between points I and D (I_ID). Enter your data into the Data Table B

Data Table B

R1= _________________	I1= _________________	IAB= _________________
R2= _________________	I2= _________________	IID= _________________
R3= _________________	I3= _________________

4. Calculate the total current through the parallel circuit Itotal

   

    using the current rule for parallel connection and compare the results with the experimental values in the table below

	Measured	Calculated	% Error
IAB
IID

Measuring Resistances

4. Find the total resistance Rtotal

   

    using Ohm’s law and the measured values of the total voltage (Vtotal

   

   ) and total current Itotal=IAB=IID

   

   .
5. Calculate the total resistance Rtotal

   

    using the parallel rule for resistances and the values of R1,R2,and R3

   

   .
6. Compare the measured and calculated values of Rtotal

   

    in the following table

	Measured	Calculated	% Error
Rtotal

Questions

1. For parallel connection is the total voltage larger, the same or smaller than the voltage across any individual resistor?

2. For parallel connection is the total current larger, the same or smaller than the current through any individual resistor?

3. For parallel connection is the total resistance larger, the same or smaller than the resistance of any individual resistor?