Summary
This lab demonstrates Ohm's law as students set up simple circuits each composed of a battery, lamp and resistor. Students calculate the current flowing through the circuits they create by solving linear equations. After solving for the current, I, for each set resistance value, students plot the three points on a Cartesian plane and note the line that is formed. They also see the direct correlation between the amount of current flowing through the lamp and its brightness.Engineering Connection
The concept of Ohm's law is the basis for explaining the relationship between resistance, current, and voltage. Electrical engineers use the equation everyday in the analysis of electrical circuits. Engineers have developed programs to do the work of predicting and optimizing the efficiency of the circuits. All electronic devices are composed of circuits, which engineers must design or debug making it essential to understand Ohm's Law. Students are asked to think about this in the postactivity assessment.
Learning Objectives
After this activity, students should be able to:
 State Ohm's law V=IR and explain the relationship between resistance, voltage and electric current.
 Calculate the electric current flowing through a circuit.
 Setup a circuit using the correct circuit components and a breadboard.
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Educational Standards
Each TeachEngineering lesson or activity is correlated to one or more K12 science,
technology, engineering or math (STEM) educational standards.
All 100,000+ K12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN),
a project of D2L (www.achievementstandards.org).
In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics;
within type by subtype, then by grade, etc.
Each TeachEngineering lesson or activity is correlated to one or more K12 science, technology, engineering or math (STEM) educational standards.
All 100,000+ K12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).
In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.
NGSS: Next Generation Science Standards  Science

Create a computational model to calculate the change in the energy of one component in a system when the change in energy of the other component(s) and energy flows in and out of the system are known.
(Grades 9  12)
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This standard focuses on the following Three Dimensional Learning aspects of NGSS:Science & Engineering Practices Disciplinary Core Ideas Crosscutting Concepts Create a computational model or simulation of a phenomenon, designed device, process, or system. Energy is a quantitative property of a system that depends on the motion and interactions of matter and radiation within that system. That there is a single quantity called energy is due to the fact that a system's total energy is conserved, even as, within the system, energy is continually transferred from one object to another and between its various possible forms.Conservation of energy means that the total change of energy in any system is always equal to the total energy transferred into or out of the system.Energy cannot be created or destroyed, but it can be transported from one place to another and transferred between systems.Mathematical expressions, which quantify how the stored energy in a system depends on its configuration (e.g. relative positions of charged particles, compression of a spring) and how kinetic energy depends on mass and speed, allow the concept of conservation of energy to be used to predict and describe system behavior.The availability of energy limits what can occur in any system. Models can be used to predict the behavior of a system, but these predictions have limited precision and reliability due to the assumptions and approximations inherent in models.Science assumes the universe is a vast single system in which basic laws are consistent.
Common Core State Standards  Math

Solve realworld and mathematical problems by graphing points in all four quadrants of the coordinate plane. Include use of coordinates and absolute value to find distances between points with the same first coordinate or the same second coordinate.
(Grade 6)
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Construct and interpret scatter plots for bivariate measurement data to investigate patterns of association between two quantities. Describe patterns such as clustering, outliers, positive or negative association, linear association, and nonlinear association.
(Grade 8)
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Interpret parts of an expression, such as terms, factors, and coefficients.
(Grades 9  12)
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Rearrange formulas to highlight a quantity of interest, using the same reasoning as in solving equations.
(Grades 9  12)
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Calculate and interpret the average rate of change of a function (presented symbolically or as a table) over a specified interval. Estimate the rate of change from a graph.
(Grades 9  12)
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Represent data on two quantitative variables on a scatter plot, and describe how the variables are related.
(Grades 9  12)
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International Technology and Engineering Educators Association  Technology

Energy can be used to do work, using many processes.
(Grades 6  8)
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Use computers and calculators in various applications.
(Grades 6  8)
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State Standards
National Council of Teachers of Mathematics  Math

make conjectures about possible relationships between two characteristics of a sample on the basis of scatterplots of the data and approximate lines of fit
(Grades
6 
8)
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Materials List
Each group needs:
 battery pack or battery holder for 4 AA batteries ($1.79 at Radio Shack)
 3, 1.5V batteries (~$0.50 each, Duracell)
 lamp ($7.50, Vernier LAMPOEK)
 wires ($3)
 breadboard ($13)
 10 Ω, 15 Ω, 22 Ω resistors ($0.99 per 5pack of each ~ $3)
Introduction/Motivation
We have been learning all about linear functions, including important characteristics and how to graph them from a variety of forms. Recall our guiding grand challenge question in which we're trying to figure out the best equation that fits the data from the research lab. In this activity, you will learn about realworld applications, such as the research where the challenge question data comes from. We will focus on Ohm's law and investigate the relationship between voltage, resistance and current. We will analyze a simple circuit as if we were electrical engineers. By knowing certain defined values within the circuit, we will be able to solve for the current flowing through the circuit using Ohm's law V=IR, or I=V/R. (Students will find that the value of current found through the calculations has a direct correlation with the brightness of the lamp.)
Figure 1 shows a diagram of the basic circuit we will be learning about within this activity. The symbol with the V next to it is the battery, because it creates the voltage. The symbol with the R next to it is a resistor, which is an item that has resistance. The symbol with lamp above it represents the light bulb that will allow us to see if current is flowing through the circuit or not.
Vocabulary/Definitions
breadboard: A perforated block of plastic that is a reusable device used to build prototypes of electrical circuits. (See Figure 2)
circuit: The complete path of electrical current through wire including any additional components including the generating apparatus, resistor(s), capacitor(s), etc.
current: The time rate flow of an electric charge (electrons) having a magnitude equal to the quantity of charge per unit of time. (units = amperes)
Ohm's law: Defined as the equation, V=IR, where V is voltage in volts, I is current in amperes, and R is resistance in ohms.
resistance: The ratio of the degree to which an object resists electrical current through it.
voltage: The difference in electrical potential between two points in an electrical circuit. Or, the rate at which energy is drawn from a power source which produces a flow of electricity in a circuit.
Procedure
Before the ActivityGather materials and make copies of the student handout.
Set up the activity following these steps:
 Attach the battery back to the three 1.5 V batteries to create a 4.5 V battery.
 Obtain a lamp and press and hold the wires to the battery pack to the lamp.
 Once the lamp is illuminated, note the brightness level.(This demonstrates the supposed circuit with no resistor with the maximum amount of current flowing through the lamp.)
With the Students
 Divide the class into groups of two or three students at each setup.
 Have students take turns setting up each circuit and make sure that each person solves for the current in each setup and creates a linear graph.
 Obtain a breadboard (the square white plastic device with lots of holes in it). It has a grid labeled on it with letters and numbers. Row X is electrically connected across the entire row. Row Y is also electrically connected. For example, A1, B1, C1, D1, and E1 are electrically connected as are F6, G6, H6, I6, and J6. The breadboard is designed this way in order to make circuit building easier by using fewer wires.
 Connect a black wire to the negative end of the battery pack and put the other end in X1 on the breadboard. Insert one end of the 10Ω resistor in X4 and the other in H4.
 Insert one end of the 15Ω resistor in X7 and the other in H7.
 Place one end of the 22Ω resistor in X9 and one end in H9.
 Once all the circuit elements are in place, connect one end of the lamp wire to the positive end of the battery and insert the other end into J4.
 What happens? Does the lamp glow as brightly as it did the first time you saw it?
 Notice that now, the electrical current is flowing from the battery, through the wires to the lamp, through the 10Ω resistor, through the black wire and back into the negative side of the battery. Refer to Figure 1 for a diagram of the circuit where R= 10Ω.
 Use Ohm's law to figure out how much current is flowing through the resistor. Don't forget units!
 Now, move the wire from the lamp to J7. The circuit that is now formed can be referenced to Figure 1 where R=15Ω.
 Does the lamp burn as brightly?
 How much current flows through the resistor now? Use Ohm's law again and don't forget units!
 Now, move the wire from the lamp to J9. The circuit that is now formed can be referenced to Figure 1 where R=22Ω.
 Does the lamp burn as brightly? What about in comparison to the last trial?
 How much current is flowing through the resistor now? Use Ohm's law again and don't forget units!
 Once you have solved all three circuits for the flow of current through the resistor, use the grid on the handout to plot a point from each circuit. The xcoordinate represents resistance and the ycoordinate represents current. Describe your results. What type of relationship is formed?
Worksheets and Attachments
Assessment
Activity Embedded Assessment
 Have students answer the questions that are placed within the procedure on the separate handout provided.
PostActivity Assessment
 Ask students to think about when they could use a resistor and Ohm's law in real life? One example would be to dim a light bulb. If students use this example, they would be correct, but this would also waste power because the resistor takes energy. For that reason, real dimmers on lights use more energy efficient circuitry. See HowStuffWorks.com for more information on dimmers.
References
Dictionary.com. Lexico Publishing Group, LLC. Accessed July 30, 2008. (Source of some vocabulary definitions, with some adaptation)
Contributors
Aubrey McKelveyCopyright
© 2013 by Regents of the University of Colorado; original © 2007 Vanderbilt UniversitySupporting Program
VU Bioengineering RET Program, School of Engineering, Vanderbilt UniversityAcknowledgements
The contents of this digital library curriculum were developed under National Science Foundation RET grant nos. 0338092 and 0742871. However, these contents do not necessarily represent the policies of the NSF, and you should not assume endorsement by the federal government.
Last modified: September 5, 2017
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