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Experiment 7: Kirchhoff’s Rules   The purpose of this lab will be to demonstrate Kirchhoff’s Rules for electrical circuits   Theory The two basic rules, most useful in analyzing electric circuits are Kirchhoff’s Rules for current and voltage

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Experiment 7: Kirchhoff’s Rules

 

The purpose of this lab will be to demonstrate Kirchhoff’s Rules for electrical circuits

 

Theory

The two basic rules, most useful in analyzing electric circuits are Kirchhoff’s Rules for current and voltage. Kirchhoff ’s Current Rule (The Junction Rule) states that at any junction (node) of a circuit, the sum of the currents entering the junction equals to the sum of the currents leaving the junction.

Iin=Iout

 

 

Kirchhoff ’s Voltage Rule (The Loop Rule) states that around any closed path (loop) in a circuit, the algebraic sum of all electric potential differences (voltages) is equal to zero.

 

Vi=0

 

 

 

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 and break the circuit and place the ammeters to complete the circuit.

 

 

 

 

 

 

Measurements

1. Construct the circuit shown on the electric circuit diagram below.

 

 

 

 

2. Measure the currents through each resistor and the total current through the battery and enter the values into the Data Table. Observe directions of the conventional currents (by checking the radio button “Conventional” on the experimental screen) and mark directions of the currents in the Data Table by placing one of following arrows: → ,↑ , ← , ↓ next to the current value in the table (copy and paste).

 

3. Measure the voltage across each resistor using voltmeter and enter the values into the Data Table

Data Table

R1=_______1Ω__________	I1= _________________	V1= _________________
R2= _______2Ω__________	I2= _________________	V2= _________________
R3= ______5.5Ω__________	I3= _________________	V3= _________________
R4= ______6.5Ω__________	I4= _________________	V4= _________________
R5= _____3Ω_____________	I5= _________________	V5= _________________
Total current: __________

 

Analysis

In this section you check Kirchhoff’s rules using your collected data.

The Junction Rule:

1. For junction A in the electric circuit diagram calculate the total current entering the junction Iintotal

   

    and total current leaving the junction Iouttotal

   

     Demonstrate that Iintotal=Iouttotal

   

   . Show your work!!

 

Iintotal=

                                                                 Iouttotal=

     

 

 

2. Repeat this procedure for junction C in the electric circuit diagram. Show your work!!

 

Iintotal=

                                                                 Iouttotal=

     

 

 

The Loop Rule:

1. For closed loop ABCA in the electric circuit diagram find the algebraic sum of all potential differences (voltages) Vi

   

    and demonstrate that this sum is equal to zero. Show your work!!

 

Vi=

 

 

Note:  in order to assign the correct sign (plus or minus) to the voltages Vi

 in the algebraic sum you have to study the Kirchhoff’s Rules in the “Electric circuits” lectures first! The lectures are posted on Yuja.

 

 

2. Repeat this procedure for closed loop ABDA in the electric circuit diagram. Pay attention that this loop includes the battery! Show your work!!

 

Vi=