Home > Using Ohm’s Law to Build a Voltage Divider

Using Ohm’s Law to Build a Voltage Divider

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Lesson Focus 
Students will design, build, and characterize one of the basic circuits of electrical engineering, the voltage divider. These circuits produce a wide range of output voltages and are building blocks for more complex circuits. Circuit design will emphasize the concepts of Ohm’s Law and students will explore mathematical relationships of parallel and series resistors. Students will demonstrate their design efforts by building prototype circuits and using test measurement tools to confirm their predictions.
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Lesson Synopsis 
Voltage dividers are a building block circuit used by Electrical Engineers to analyze resistance and optimize electronic devices. In this lesson students apply Ohm’s Law to construct voltage divider circuits. Students learn how to read resistor codes and calculate resistor values. Using breadboards, students build voltage dividers and predict and measure output voltage values. Students are given the electrical requirements for an LED, and are then challenged to design and verify a voltage divider circuit to illuminate it.

Age Levels:

  • Understand and demonstrate the engineering design process
  • Use Ohm's Law as a tool for engineering design.
  • Use a digital multimeter to collect data.
  • Analyze the electrical requirements of light emitting diodes (LED’s).
Anticipated Learner Outcomes 

As a result of this activity, students should develop an understanding of:

  • The engineering design process
  • The relationship between voltage, current, and resistance in an electrical circuit
  • basic breadboard and measurement techniques

Lesson Activities

The activity consists of using a nine-volt battery to:

  • Predict the output voltage of a simple voltage divider using Ohm’s Law and derived equations.
  • Design, build, and demonstrate a simple voltage divider circuit.
  • Measure and record the voltage produced and compare to the predicted value.
  • Use the concepts and techniques to design a circuit for a high intensity light emitting diode.

Four teacher handouts are provided:

  • Step By Step Guide
  • Appendix 1: Equations for Series and Parallel Resistance
  • Appendix 2: Matrix of Possible Voltage Outputs
  • Appendix 3: Advanced Equations for Voltage Divider Ratios

Three student handouts are provided for advance review:

  • Voltage Divider Information Sheet
  • Resistor Color Codes
  • Step By Step Procedures

Alignment to Curriculum Frameworks

Curriculum alignment sheet is included in PDF.

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