Simple Resistive Circuits

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xxxxxxxxxxxxx (Fall 2020) Lab:

 

Title: Simple Resistive Circuits

 

Student name: xxxxxxxxxxxxxxxxx Student ID: xxxxxxxxxxx Major: xxxxxxxxxxxxxxxx                 Date: 11/18/2020

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Check list:

• Cover Page
• Aim
• Introduction
• Experiment
• Results
• Conclusion (One paragraph)
• Post-Lab Question

 

 

 

 

Aim

 

• To apply Ohm’s law on simple resistive circuits.

Introduction

Ohm’s law is fundamental law states that the voltage between two points in a wire is directly proportional to the current passing through the wire and the current is; directly proportional to the resistance of the wire or circuit (Kelvin). Ohm’s law is mathematically represented using the formula V=IR where; V= voltage, I= current, R= resistance. Ohm’s law is used to provide a simple relationship between voltage, current, and resistance, which are critical components of electricity. The unit of resistance is ohms, which is denoted by Ω (Kelvin). Ohm’s law is the most-used law of electricity that is useful in calculating power, voltage, current, and the resistance of an electrical circuit and finds application when determining any of the components is required through a simple calculation.

The materials that obey ohm’s law are classified as Ohmic materials, while that do not obey ohm’s law are referred to as nonohmic materials. Ohm’s law is limited to various applications since it does not work with unilateral networks, which allow current to flow only in one direction. This law is not applied to non-linear elements that have varying current compared to the applied voltage. This implies that the conducting material’s resistance varies by changing voltage and current.

In a typical Ohm’s experiment, the current is monitored using an ammeter placed in series with the resistors, and the voltage measured using a voltmeter. When the circuit is connected, the voltage and current are measured, and the resistance of the circuit is determined using the equation V=IR, therefore, R=V/I. The flow of current can be reversed by interchanging the batteries’ terminals and measuring the current and voltage in a reverse direction.

Experiment

 

Figure 1: The image above represents a circuit with three resistors and a potentiometer connected to a power supply. While switch S1 is open, we measure vR1, vR2, and vR3.

 

 

Figure 2: The image above represents a circuit with four resistors connected to a power supply. While switch S1 is closed, we measure iR2, iR3, and iR4.

 

Results

 

Variable	vR1	vR2	vR3	vR1 + vR2 + vR3
Value	10 – 8.7341 =         1.2659 v	8.7341 – 5.9493 =   2.7848 v	5.9493 v	10 v

 

Variable	iR2	iR3	iR4	iR2 + iR3 + iR4
Value	1.7785 mA = 1.7785×10^-3 A	916.76 μA = 9.1676×10^-4 A	861.75 μA = 8.6175×10^-4 A	3.55701×10^-3 A

 

R4	iR1	vR1
0%	3.1250 mA = 3.1250 ×10^-3 A	10 v
20%	2.1725 mA = 2.1725 ×10^-3 A	10 v
40%	1.8654 mA = 1.8654 ×10^-3 A	10 v
60%	1.7136 mA = 1.7136 ×10^-3 A	10 v
80%	1.6232 mA = 1.6232 ×10^-3 A	10 v
100%	1.5632 mA = 1.5632 ×10^-3 A	10 v

Figure 3: the image above represents parameter sweep for R4 with the output as iR1 on MultiSim.

Figure 4: the image above represents parameter sweep for R4 with the output as VR1 on MultiSim.

 

Conclusion

In this experiment we learn how to create two simple resistive circuits and use ohm’s law to understand the relation between the current and the voltage. the first circuit is a resistive series-parallel circuit with an open switch, three resistors, and a potentiometer all connected to a power supply. We run the circuit on Multisim and start taking note of the three resistors voltage values then add them all up to get the total voltage of the circuit. Second, we create a distinct circuit by replacing the potentiometer with a fourth resistor and a closed switch. After running the circuit, we take note of the current values in R2, R3, and R4. Third, we manually adjust the values of R4 in steps of 20% starting from 0% till we reach 100% we take note of the observed values of IR1 and VR1. Fourth, we conduct a parameter sweep for R4 with the results as IR1 and observe the change in the graph. Finally, we conduct a parameter sweep for R4 with the results as VR1 and observe the change in the graph.

Discussion

After we have done the experiment, we notice the vary in the output of iR1 specially when R4 values are changing while the voltage remains the same. We can see clearly the inverse correlation in both graphs. Therefore, if R4 value is increased total power delivered by the voltage will decrease.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Work cited

Tenny, Kevin M., and Michael Keenaghan. “Ohm’s Law.” (2017).