Lesson 5. Voltage, Resistance, and Current: Lab Investigation

Melissa Beemsterboer
Physics
45 minutes
High School Honors Physics
v1

Overview

In this lesson, students will circuitry materials to perform a lab to discover the relationship between resistance and current. They will need to think about and discuss what their variables will be, what tools they will use to measure them, and how many times to change the independent variable to measure the dependent variable. They will also need to think about what to control, and how to communicate their data once they have a data table.

Students often come to physics with a misconception that "3 trials is enough." This is largely due to experiences they may have had in biology and chemistry, where lab resources may be expensive, limited, and hard to come by. It is quite common for a biology or chemistry teacher to limit investigations to 3 trials simply to help them see a change in data with a limited amount of resources.

In physics, students often have fewer limitations on resources. In this lab investigation, aim to provide each group with at least five different resistors. More would be better. This way students will have to decide how many trials is "enough" to be confident about their data. Teachers should encourage students to put their data into a graph as a means of communicating whatever relationship they find. If they do this, then they will need to come to the conclusion that 3 data points is not enough to create a graph with a defined shape. They will need to change and measure the variables more than 3 times.

Note: You may need to review with your students how to tell the resistance of each resistor based on the colored bands, if the resistors you are providing have colored bands. This link might help: https://www.wikihow.com/Read-Axial-Lead-Resistors

 

Standards

Next Generation Science Standards
  • Engineering, Technology, Applications of Science
  • Physical Science
  • NGSS Crosscutting Concept
    • Systems
    • Energy
  • NGSS Practice
    • Analyzing Data
    • Constructing Explanations, Designing Solutions
    • Using Models
    • Using Mathematics
    • Conducting Investigations
Computational Thinking in STEM
  • Data Practices
    • Analyzing Data
    • Collecting Data
    • Visualizing Data
  • Modeling and Simulation Practices
    • Assessing Computational Models
    • Constructing Computational Models
  • Computational Problem Solving Practices
    • Computer Programming
    • Troubleshooting and Debugging

Credits

Unit designed by Melissa Beemsterboer a teacher at Lindblom.

Activities

  • 1. Plan your Investigation
  • 2. Perform your Lab Investigation
  • 3. Analyzing your Lab Data

Student Directions and Resources


In this lesson you will be setting up a circuit to perform an actual lab investigation. You will not only need to determine what your independent and dependent variables will be, you will also have to think deeply about other facets of planning an effective lab investigation.

1. Plan your Investigation


Next you will design a lab to investigate the relationship between resistance and current. You will need to be thoughtful in designing this lab to be sure you get a quantity and quality of data that you can trust. All labs have errors, but no errors should be preventable.

With your group, discuss your plan for investigating this relationship. Beyond knowing what the independent and dependent variables are, you should also think about:

  • What variable(s) will you control?
  • How many times will you change the independent variable?
  • How will you quantitatively change the independent variable?
  • How will you measure the dependent variable each time you change the independent variable?
  • Once you have your data, how will you communicate it to others? (Hint: A data table is never the easiest way for a reader to determine the relationship between two variables.)

Your teacher will let you know how much time you have to discuss this lab procedure. Once you are confident about the procedure you have written down, call your teacher over to check. Your teacher will give you the go ahead to begin the lab.

Note: Your teacher may need to review with you how to tell the resistance of each resistor based on the colored bands.

2. Perform your Lab Investigation


  1. Use the simulation at right to perform the lab investigation you designed. If you feel you have done something in error, feel free to stop what you are doing and start the trial again.
  2. Collect your data below. You will then need to decide how to communicate your data so it can be easily understood by the public.

 

 

 

 

 


Question 2.1

Enter your data in the table below. To add more data, click the + symbol in the bottom row.

3. Analyzing your Lab Data


What is the relationship between resistance and current in a circuit? Sharing your data table with the public is not enough. It is very difficult to determine a relationship simply looking at a series of numbers. It is much better to view relationships with a trend line.

Create a trend line of your data using Google Sheets. Make sure to share the Google Sheet with your group mates and your teacher when you are finished. Then answer the question below.


Question 3.1

What is the relationship between resistance and current?



Question 3.2

Challenge Question: How does voltage relate mathematically to resistance and current?

(What is a mathematical equation that relates voltage (V), current (I), and resistance (R)?)



Question 3.3

Take a screen shot of your graph/trend line and attach it here. (If you're not sure how to take a screen shot, Google it.)

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