Discovering and Applying Ohm's Law

Learning Resource Type

Lesson Plan

Subject Area

Science

Grade(s)

9, 10, 11, 12

Overview

Students will design an experiment to relate the voltage difference and current in a circuit. They will collect data, then create and analyze a graph in order to arrive at Ohm's Law. They will create circuits and determine the voltage difference, current, and resistance in the circuit using Ohm's Law.

This lesson results from the ALEX Resource Gap Project.

Science (2015) Grade(s): 09-12 - Physics

SC15.PHYS.12
Use the principles of Ohm’s and Kirchhoff’s laws to design, construct, and analyze combination circuits using typical components (e.g., resistors, capacitors, diodes, sources of power).

Vocabulary

ammeter
voltmeter
series
parallel
model
Kirchhoff's laws
Ohm's law
resistance
current
electric potential
multimeter
positive
negative
electrical components
circuit
voltage source
conductors
resistor color code
circuit diagram
heat
charge
static electricity

Knowledge

Students know:

The color code for the resistance of resistors.
The basic principles of static electricity.
How to construct electrical circuits.
Several different components can be used to build an electrical circuit.

Skills

Students are able to:

Design and use models.
Develop an appropriate experimental procedure.
Create a data sheet.
Collect and organize experimental data.
Follow written and verbal instructions.
Make measurements using standard units.
Effectively manipulate laboratory equipment.
Work safely in collaborative lab groups.
Manipulate equations.
Interpret graphical data.
Solve mathematical equations.
Use a multimeter.

Understanding

Students understand that:

Circuits are complete pathways through which current will flow predictably and will provide energy to the connected component(s).
Circuits may be simple or complex.

Scientific and Engineering Practices

Analyzing and Interpreting Data

Crosscutting Concepts

Cause and Effect

Primary Learning Objectives

Students will discover and apply Ohm's law by analyzing data.

Students will use the principles of Ohm’s law to design and construct a circuit.

Procedures/Activities

BEFORE: Have students sketch (on their own paper) a simple circuit with all three major components. Ask for three volunteers to draw their circuits on their whiteboard, show the class, and see if all students agree that what they have drawn is a complete circuit.

DURING: Pose the question - What is the relationship, if any, between the voltage difference and the current in a circuit?

Part I

Students should develop and carry out a procedure to measure voltage difference and current. They should keep one resistor in the circuit and change only the voltage difference or the current, then record the new data. It is at the student/teacher's discretion how many points of data to collect (6 is recommended). At the end of the experiment, they should have several points of data that include current and voltage differences for each point.

*BE SURE TO APPROVE THE STUDENTS' PROCEDURE BEFORE THEY PERFORM THE EXPERIMENT*

A sample procedure can be found in the "Sample Student Report".

Part II

After the students collect the data, they should graph using the Logger Pro software and do a 4-step analysis of the graph.

1) Write the equation of a line
2) Replace X and Y with the experimental variables.
3) Replace m and b with their values from the graph.
4) Write the final equation (the mathematical relationship). Determine the significance of the slope by looking at what was held constant in the equation.

Part III

Assign students the post-lab questions to practice using Ohm's Law, which they will have just discovered.

AFTER: Have students present their results by writing their findings on the whiteboard or interactive whiteboard. All groups should present their graph and 4-step analysis. Each group should also have an assigned question from the worksheet to present. Students should present their graph and explain how the graph led them to the discovery of Ohm's Law. They should also work through their assigned problem. Allow other groups to ask the presenting group questions.

Assessment Strategies

Formative:
Teacher observation
Exit Ticket (Day 1 - Draw your data table. This lets the teacher know if the student has collected the appropriate data during the lab - essentially, it lets the teacher know if the first part of the lab was successful)

Summative:
Whiteboarding (each student in the group must talk - this allows the teacher to informally assess individual students)
Lab Report
Quiz (see "Ohm's Law Quiz")

Acceleration

Students seeking to expand their understanding of Ohm's Law and circuits can complete the activity in the "Extension" document.

Intervention

Students needing additional help can do the PhET Simulation: Ohm's Law.

Total Duration

91 to 120 Minutes

Background/Preparation

Before this activity, the teacher should introduce students to the:

definition of a circuit.
components of a circuit
open vs. closed circuit.
sketching a circuit.

Students should be familiar with the concept of circuits - essentially, components of circuits and definitions of the voltage difference, current, and resistance. Students should also know the equation of a line.

Materials and Resources

Each group of 4 Students:
Computer with internet access and Logger Pro, DC variable power supply, connecting wire with alligator clips (set of 3), 1 resistor (10 Ω is recommended), 1 whiteboard, dry-erase markers, paper, pencil, handout "Ohm's Law Lab" (see attached document).

*Logger Pro is available for free to any Alabama Science in Motion trained teacher - see your specialist for details. Other graphing software such as Graphical Analysis or even Excel could be used, although Logger Pro is recommended.

Each student will need a copy of the Exit Ticket

Each student will need a copy of the Ohm's Law Quiz. An answer key is provided for the teacher.

Each student will need a copy of the Post Lab Questions.

*Students needing acceleration will need a copy of the Extension Activity and one additional resistor.

*Students requiring intervention will need access to this website: https://phet.colorado.edu/en/simulations/ohms-law

The teacher will need copies of all documents.

Technology Resources Needed

Each group of 4 will need a computer with internet access and Logger Pro (or other graphing software as indicated above).

Approved Date

2017-05-27