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LAB REPORT 4

KIRCHHOFF’S LAWS

Date of Experiment: March 26th, 2021 Date of Report: March 27th, 2021 Members: 1. Nguyễn Thiên Ân EEEEIU19001 2. Nguyễn Hữu Luân ITITIU19027 3. Trương Nhật Minh Quang ITITIU19194 4. Trần Nam Tuấn ITITIU19230 5. Võ Ngọc Duy Nguyên ITITIU19167

Experimental Data: Table 4.1 Resistance (Ω)

Voltage (V)

Current (mA)

R1

217 Ω

V1

0.5 V

I1

2.18 mA

R2

55.9 Ω

V2

0.89 V

I2

13 mA

R3

10.4 Ω

V3

0.25 V

I3

23.6 mA

R4

99.3 Ω

V4

1.14 V

I4

10.24 mA

R5

18.3 Ω

V5

0.25 V

I5

11.21 mA

RTotal

51.6 Ω

VTotal

1.4 V

ITotal

24.8 mA

Using the schematic of the circuit, calculate the total resistance of the circuit. Record the value in the Table. 4.1. Based on the calculated resistance and the voltage across A and B, calculate the theoretical value of the current using Ohm’s Law. Total current (theoretical) = 27.1 (mA) Calculate the percent difference between the theoretical current and the measured current:

%diff=

theoretical-measured ×100% theoretical

27.1 mA −24.8 mA x 100 %= 8.48 % 27.1 mA There was a huge percentage of difference between Theoretical and Measured values of the current because of the length of wires and their qualities due to ages. Otherwise, resistors’ values also affected a lot on measured current.

Write down the Kirchhoff’s current law at the junctions A, B, C, and D into the table below. Use the experimental data above to find the net current flowing into (or out of) the junctions. Junction

Kirchhoff’s current law

Current (mA, calculation)

Current (mA, measure)

A

ITotal = I1 + I3

ITotal

25.78 mA

ITotal

24.8 mA

B

I2 + I4 = ITotal

ITotal

23.24 mA

ITotal

24.8 mA

C

I1 + I5 = I2

I1

1.79 mA

I1

2.18 mA

D

I5 + I4 = I3

I3

21.45 mA

I3

23.6 mA

Compare the currents calculated from Kirchhoff’s current law and those measured from experiment. Does the Kirchhoff’s current law hold true in the experiment? Junction A: %diff = 3.8% Junction B: %diff = 6.7% Junction C: %diff = 21.7 % Junction D: %diff = 10.02% In this experiment, with 4 junctions appeared in the circuit, directly Kirchhoff’s Current Law could be use in this experiment due to currents’ direction.

Write down the Kirchhoff’s voltage law for 4 different loops. For each loop, use the experimental data above to find the potential difference between a chosen component. Loop

Kirchhoff’s voltage law

Voltage (V, calculation)

Voltage (V, measure)

VR1R5R4

V1 – V5 + V4 – V0 = 0

V1

0.51

V1

0.5

VR3R5R2

V3 + V5 + V2 – V0 = 0

V3

0.26

V3

0.25

VR1R3R5

V1 – V5 – V3 = 0

V1

0.5

V1

0.5

VR2R5R4

V5 + V2 – V4 = 0

V2

0.89

V2

0.89

Compare the voltages calculated and those measured from experiment. Does the Kirchhoff’s voltage law hold true in the experiment? Loop R1R5R4: %diff = 1.96% Loop R3R5R2: %diff = 3.86% Loop R1R3R5: %diff = 0% Loop R2R5R4: %diff = 0% Throughout in this experiment, the Kirchhoff’s voltage law did hold true because voltage dropped around each loop with resistors.

Experimental Data: Resistance (Ω)

Voltage (V)

Current (mA)

R1

217 Ω

V1

1.08

I1

5.17

R2

55.9 Ω

V2

0.27

I2

5.17

R3

10.4 Ω

V3

0.05

I3

-4.25

R4

99.3 Ω

V4

0.56

I4

9.46

R5

18.3 Ω

V5

0.17

I5

9.53

V01

1.41

I01

5.14

V02

1.55

I02

9.53

Write down the Kirchhoff’s current law at the junctions A and B into the table below. Use the experimental data above to find the net current flowing into (or out of) the junctions. Junction

Kirchhoff’s current law

Current (mA, calculation)

Current (mA, measure)

A

I2 = I3 + I4

I2

5.21

I2

5.17

B

I01 = I5 + I3

I5

9.39

I5

9.53

Compare the currents calculated from Kirchhoff’s current law and those measured from experiment. Does the Kirchhoff’s current law hold true in the experiment?

I2 %diff = 0.76% I5 %diff = 1.49% The Kirchhoff’s current law does hold true in the experiment because there are 2 junctions A and B in this circuit with current runs through.

Write down the Kirchhoff’s voltage law for 3 different loops. For each loop, use the experimental data above to find the potential difference between a chosen component. Loop

Kirchhoff’s voltage law

Voltage (V, calculation)

Voltage (V, measure)

V1R1R2R3

-V01 + V1 + V2 + V3 = 0

V1

1.09

V1

1.08

V2R5R3R4

-V02 + V5 – V3 + V4 = 0

V3

0.18

V3

0.15

-V01 + V1 + V2 + V4 – V02 + V5=0

V4

1.44

V4

1.56

V1R1R2R4V2 R5

Compare the voltages calculated and those measured from experiment. Does the Kirchhoff’s voltage law hold true in the experiment? Loop R1R2R3 %diff = 0.92% Loop R5R3R4 %diff = 16.67% Loop R1R2R4V2R5 %diff = 8.33% After the measurement, we assumed that, by using the Kirchhoff’s voltage law in loops, every measured numbers are not different so much as the calculation above, due to wires and resistors age and qualities....