Precision Resistor Circuit Accuracy Experiment

Objective

The goal of this experiment is to investigate the accuracy of a circuit that utilizes precision resistors, and to compare the calculated theoretical values with the actual measured values to understand the importance of resistor accuracy in sensitive circuits.

Components Required

• 2 x Precision Resistors (1% or 0.1% tolerance)
• 2 x Regular Resistors (5% tolerance)
• 1 x Multimeter (for measuring resistance, voltage, and current)
• 1 x Power Supply (DC source)
• 1 x Breadboard
• 1 x Load (LED or small motor)
• Connecting Wires

Theory

Precision resistors are resistors that are manufactured with tight tolerances, meaning their actual resistance is very close to their nominal (labeled) value. In critical circuits where accuracy is essential, such as in measurement instruments or calibration equipment, precision resistors are used to ensure consistent performance. Regular resistors, on the other hand, have wider tolerances and can introduce variations in circuit behavior. This experiment will compare the performance of a circuit with precision resistors against one with regular resistors to highlight the differences in accuracy.

Circuit Diagram

Experimental Setup

1. Construct a simple voltage divider circuit using two precision resistors.

2. Measure the output voltage of the divider using a multimeter, and compare it to the theoretical value calculated using Ohm's law.

3. Repeat the same setup with two regular resistors of the same nominal values, and observe the difference in accuracy.

Procedure

1. Place the two precision resistors (e.g., 1kΩ with 0.1% tolerance) in series on the breadboard.
2. Connect the power supply across the resistor network, with a voltage of 5V.
3. Measure the output voltage at the junction of the two resistors using a multimeter.
4. Calculate the expected output voltage using the voltage divider formula:
   V_out = V_in × (R2 / (R1 + R2))
5. Compare the measured output voltage with the calculated value to assess the accuracy.
6. Replace the precision resistors with regular resistors of the same nominal value (1kΩ, but with 5% tolerance).
7. Measure the output voltage again and compare it to the theoretical value.
8. Repeat the experiment with different resistor values if desired, and note any differences in the results.

Results and Observations

Record the following measurements:

• Voltage output with precision resistors
• Voltage output with regular resistors
• Theoretical voltage output

Analyze the deviation of the measured values from the theoretical value, and compare how precision and regular resistors affect circuit accuracy.

Conclusion

In this experiment, we observed how the tolerance of resistors influences the accuracy of a circuit. Precision resistors provided results much closer to the theoretical calculations, making them essential in high-accuracy applications. Regular resistors, due to their higher tolerance, introduced greater variation, leading to less predictable behavior. This highlights the importance of selecting the right components for circuits where precision is crucial.