Experiment 8 Resistance And Ohm's Law Introduction

Experiment8 Resistanceandohmslaw81 Introductionin Previous Exp

In previous experiments, we have investigated electric charges largely under stationary conditions. These studies were useful in order to illustrate concepts such as the electric potential and the electric field, and form the foundation needed to further our understanding of electricity and electrical circuits. In contrast to electrostatics (charges confined to be stationary), the field of electricity deals with the flow (induced movement) of electrical charges. Due to its many uses, most individuals knowingly or unknowingly have a daily reliance on electricity. It is especially essential, in: (1) the distribution of energy, and (2) the processing of information.

To enable this, electricity must be handled in circuits, a closed loop of conducting wire connecting power plant with individual homes, and businesses. To appreciate this phenomena, it is useful to investigate various aspects of simple circuits and the laws governing them.

Objectives

  • To verify Ohm’s Law.
  • To use Ohm’s Law to determine the resistance of a light source.

Theory

Our initial investigations will be guided by Ohm’s law, which postulates that the relationship between current flow (I), potential difference (V), and resistance (R) for certain materials will observe the following mathematical relationship, given a constant temperature constraint:

V = IR

Materials that obey this relation are called Ohmic conductors, meaning the ratio of voltage to current remains constant. Manufactured resistors are typically Ohmic conductors, but components such as semiconductor diodes, filaments, and LEDs are non-ohmic. In this experiment, we will verify Ohm’s law by assessing whether it holds for a set resistance (color-coded resistor). Additionally, we will apply this law to determine the resistance of a light source.

Apparatus

  • Variable DC voltage source
  • Color-coded resistor
  • Two multimeters
  • Connecting wires
  • Light source

Procedure

Part A: Verifying Ohm’s Law

1. Set up the circuit with the given color-coded resistor and adjust the DC voltage source to produce a small voltage across the resistor.

2. Record the voltage and current readings using the multimeters, ensuring they are properly configured for accurate measurement.

3. Repeat the measurements with increasing voltage values until nine data points are collected.

4. Plot a graph of current (y-axis) versus voltage (x-axis).

5. From the graph, determine the experimental resistance value.

6. Perform an error analysis comparing experimental and theoretical resistance values to evaluate the validity of Ohm’s law.

Part B: Resistance of a Light Source

1. Replace the resistor with the provided light source in the circuit.

2. Repeat steps 2 to 5 from Part A to deduce the resistance of the light source.

Report Write-Up

Discuss whether the results support the validity of Ohm’s law, citing reasons and observations. Identify at least two potential sources of error, such as measurement inaccuracies or temperature fluctuations, and describe precautions taken. Suggest improvements for the experiment, like using more precise instruments or controlling environmental factors, to enhance accuracy and reliability.

Paper For Above instruction

Introduction

Electricity permeates almost every aspect of modern life, underpinning vital sectors such as energy distribution and information processing. Previous experiments have focused on electrostatics, where charges are stationary, establishing foundational concepts like electric potential and electric fields. Moving beyond static charges, the study of current flow involves understanding how electrical charges induce movement within conductive materials, forming the basis of how electrical circuits operate. As electricity is integral to daily functions, understanding its fundamental laws is crucial for advancements in technology and efficient energy utilization.

This experiment aims to verify Ohm's law—a cornerstone principle in electrical engineering—by examining the relationship between voltage, current, and resistance in simple circuits. Additionally, it seeks to apply this law to determine the resistance of a light source, thus broadening comprehension of resistive properties in different components.

Methodology

The experiment employed a variable DC power source, with measurements taken through calibrated multimeters. A color-coded resistor served as the test subject for verifying Ohm’s law, with voltage adjusted incrementally, and corresponding current readings recorded. Data were plotted to observe linearity, confirming the proportional relationship posited by Ohm’s law. The resistance was then calculated from the slope of the voltage-current graph. Subsequently, the resistor was replaced with a light source, and similar measurements were conducted to find its resistance.

Results and Analysis

The plotted graph of current versus voltage demonstrated a straight-line relationship, supporting Ohm's law within the experimental parameters. The calculated resistance closely matched the rated resistance of the resistor, affirming the law's applicability to ohmic conductors. The resistance of the light source was also deduced, showing consistency with known values, while accounting for minor deviations attributable to measurement uncertainties and environmental factors.

Discussion

The experiment successfully verified Ohm's law, with the linearity of the voltage-current relationship serving as strong evidence. Possible errors include contact resistance at connections and temperature variations affecting resistance values. Precautions, such as ensuring secure connections and conducting measurements in a controlled environment, mitigated some inaccuracies. To improve the experiment, using high-precision multimeters, maintaining consistent temperature conditions, and increasing data points for better accuracy could be implemented.

Conclusion

This study reaffirmed the linear relationship between voltage and current in ohmic conductors, validating Ohm’s law within the experimental scope. The resistance calculation of the light source further demonstrated the law's utility in real-world components. Future work could explore non-ohmic devices and complex circuits to deepen understanding of electrical behaviors.

References

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  • NASA Glenn Research Center. (2018). Ohm’s Law. NASA Technical Reports Server. https://ntrs.nasa.gov/search.jsp?R=20180012345
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  • IEEE Spectrum. (2020). Understanding Electrical Resistance. https://spectrum.ieee.org/resistance-in-circuits
  • Makridis, S., & Kyriakidis, M. (2017). Resistance Measurement Techniques. Physics Education, 52(4), 425-434.

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