Lesson Plan Topic6: Using an Oscilloscope to Determine the Wave Speed of a Solid Metal Object
I chose this activity to give my students practice using an oscilloscope and to mathematically calculate the speed of a sound wave based on reading from the scope.
Background:
An oscilloscope is an instrument used to test and/or monitor electricity through a circuit. There is an input for electrical current and an output for the circuit. An oscilloscope has the ability to show a variety of graphs and functions of what is being studied. This lab activity will give the students a chance to measure the speed of a longitudinal wave through a long metal object when it is hit by another metal object. This setup involves a complete circuit when the objects are hit together and vibrate to break and reconnect the circuit. This allows an electrical pattern that can be registered through an oscilloscope.
Student objectives:Students will learn how to operate the basic parts of an oscilloscope and make measurements that will be used to calculate the wave speed through a metal object.
The following state standards will be met with this activity material covered in the unit.
9-12.N.2.1. Students are able to apply science process skills to design and conduct student investigations.
9-12.N.2.2. Students are able to practice safe and effective laboratory techniques.
9-12.N.2.1A. Students are able to manipulate multiple variables with repeated trials.
9-12.P.3.1A. Students are able to explain wave behavior in the fundamental processes of reflection, refraction, diffraction, interference, resonance, and image formation.
9-12.P.2.1. Students are able to apply concepts of distance and time to the quantitative relationships of motion using appropriate mathematical formulas, equations, and units.
9-12.P.3.2. Students are able to describe how characteristics of waves are related to one another.
Time: 90 minutes of class time.
Materials:Oscilloscope with probes, a long metal rod or object, a metal object to hit with, 2-3ft pieces of insulated wire, and a 3 volt battery
Activity: In a group or team the students will:
- Put together a circuit that includes the one end of the rod connected to one end of the probe.The other end of the probe is connected to one electrode of the battery. The other end of the battery is connected to a wire that is connected to the other metal object.
- Turn on the oscilloscope and hit run
- Strike the metal rod with the metal object making sure to let the metal rod vibrate the metal object.
- Read the time between the peaks on the oscilloscope
- Measure the length of the metal rod and multiply it by 2 and divide by the time between peaks and record the speed in meters per second.
Notes: This activity needs to be done with 3 different trials on 3 different types of metals.
Student assessment: Students will be assessed on their lab write-up/journals to include the answers to the following questions:
Which metal produced the fastest speed?
Why did you multiply the length on the metal by 2 for your calculations?
Use the internet to find the vibration speeds for the metals you tested and compare your results
with them.