Experiment 8 - Kirchhoff\'s Rules - Using Ph ET Simulation-1 PDF

Preview

Summary

lab...

Description

Experiment 8: Kirchhoff’s Rules Objective 1. Learn to build up a complicated circuit by using one or two DC power supplies and three to five resisters. 2. Use PhET interactive simulation tool (Circuit Construction Kit AC Prototype) to build the circuits and verify Kirchhoff’s rules.

Theory Simple electric circuits, normally with a single voltage source, can usually be solved by reduction schemes: replacing parallel and series combinations with their equivalent resistance. A complicated circuit are neither parallel nor series arrangements and require more powerful methods. Kirchhoff’s rules give a simple approach to solve these type of circuits. Kirchhoff’s rules have two parts (1) Junction rule: states that the current(s) entering a junction (node) equals the current(s) leaving the junction. (2) Loop Rule : states that the voltage drops across each circuit element around a closed circuit path sum up to equal zero.

A

B

Junction Rule:

I 1 +I 2=I 3 （ 1） I3 F

E

Loop Rule: Loop ABEFA

ε 1−I 1 R 1− I 3 R3=0 ( 2) D

C Figure 1

Loop Rule: Loop CDEFC

ε 2 −I 2 R 2− I 3 R3 =0(3)

Equipment PhET interactive simulation tool (Circuit Construction Kit: DC - Virtual Lab) https://phet.colorado.edu/en/simulation/circuit-construction-kit-dc-virtual-lab

Procedures Build the circuit as shown in Figure 1 by using PhET Simulation Tool 1. Click the above http link, you will see

2. Click ▲, you will see

3. Now you build your circuit by using “wire”, “Battery” and “Resistor”

4. You can tap the circuit elements to change it value by adjust

5. You can also toggle between the battery and the battery symbol as shown above. 6. Use the circuit board to build the circuit as shown in the above Figure 1, and setup R1=120 Ω , R2=80.0 Ω , R3=50.0 Ω , ε 1=10.0V , ε 2 =8.0 V .

A. Measure electric potential and voltage drop and verify Kirchhoff’s rules 1. Use the circuit board tool Voltmeter to measure the voltage by simple drag the Voltmeter to the necessary location as shown in the following figure.

2. Connect the COMMON terminal (black color) of the voltmeter to point F, defining the potential at point F is zero. Measure 1.

VA ,

VB ,

V C , V D , and V E . Record their values to the table

Data Table 1 VA

V F =0 10 Potential Difference

∆ V FA (V A −V F ) 10

VC 8

VB 4.99

∆ V AB (V B −V A ) -5.5

VE 4.99

∆ V EF (V F −V E ) -4.99

VD 4.99

∆ V CD (V D−V C 8

∆ V BE (V E−V B)

∆ V DE (V E−V D )

8

B. Measure current and verify Kirchhoff’s rules 1. Measure the voltage across each resister (it should be the same as potential drops

∆ V AB ,

∆ V CD , and ∆ V EF ). Record their values on the table 2. 2. Using Ohm’s law calculate the currents for each resister and put the values on table 2.

3. Use the circuit board tool Ammeters to measure the current by simple drag the Ammeters to the necessary location, and cut the circuit open, then let the local current path through the Ammeters as shown in the following figure. Note that the Ammeters should be in series with the resister.

4. Use the circuit board tool Ammeters measure the current passing through each resister. Record their values on the table 2. 5. Calculate the current passing through each resister by using equation 1 to 3. Compare it with the experimental current, and find the percentage error.

Use Data Table 1 to Check Kirchhoff Loop Rule Check Loop ABEFA:

¿ ¿ ¿ ¿ ∆ V FA +∆ V AB +∆ V BE+∆ V EF =¿ ¿

Check Loop CDEFC:

¿ ¿ ¿ ¿ ∆ V FC+ ∆ V CD + ∆ V DE + ∆ V EF =¿ ¿

Your conclusion:

Data Table 2 1

2

3

4

5

Measured Voltage

Calculated Current (Using Ohm’s Law)

Measured Current

Calculated Current (Using Equation 1-3)

% error (compare

column 3 and 4)

R1

∆ V AB

.046

.03

1.34

0.87

R2

∆ V CD

.088

.04

0.76

0.12

R3

∆ V EF

.089

.09

1.22

2.09

** Currents in column 2 and 4 should be very close

Additional Circuits Use PhET interactive simulation tool (Circuit Construction Kit AC Prototype) to build the following circuits and verify Kirchhoff’s rules....