Electromagnetic Induction

While completing the experiment Electromagnetic Induction, make sure to keep the following guiding questions in mind:

· Is the magnitude of the magnetic field the primary determinant in the Emf induced in the coil? If not, then what is the primary determinate of the magnitude of the induced Emf?

· How is relative motion between the field and coil induced? What controls do you have for changing the relative motion? What is the relationship between the units of RPM and radians per second?

· How can ratios be used in an experiment when data is only available in the form of relative magnitudes?

To complete the experiment you will need to:

1. Be prepared with a laboratory notebook to record your observations.

2. Click the image to open the simulation experiment.

3. Perform the experiment as described.

4. Transfer your data and results from your laboratory notebook into the lab report template provided at the end of this experiment description.

5. Submit your version of the laboratory experiment report.

In your laboratory notebook, you will collect data, make observations, and ponder the questions posed within the lab instructions. Thus, the notebook should contain all the data collected and analysis performed, which will be invaluable to you as you write the results section of your laboratory report. Furthermore, the notebook should contain your observations and thoughts, which will allow you to address the questions posed, both for the discussion section in the laboratory report and in helping you to participate in the online discussion included in the module.

M4A1 Experiment: Electromagnetic Induction

PART I – Faraday’s Law and Relative Motion

Start the simulation “Faraday’s Electromagnetic Lab ” by clicking on the image below:

http://phet.colorado.edu/sims/faraday/faraday_en.jnlp

http://phet.colorado.edu/sims/faraday/faraday_en.jnlp

· Select the tab labeled “Pickup Coil.”

· Move the bar magnet to various static (“nonmoving”) positions.

Note that any static position from which the magnet seems to induce a potential in the coil seems to cause the bulb to shine brightly. Try various static positions, including near and far positions. Use the simulation controls to flip the field. Note your observations in your laboratory notebook. Pick other controls available in the simulation to vary the field. What do your observations imply about the magnitude and direction of the magnetic field in inducing an electromotive force in the pickup coil? Do your observations indicate any other factors that might induce an EMF in the pickup coil, and thus, cause the bulb to shine?

Note any factors that will induce an EMF in your notebook. Investigate the general relationship between the magnitude of the bulb brightness and the particular factor you are considering. Your investigation should indicate whether bigger, faster, further, or more causes the bulb to burn brighter than the converse.

Part II – Parameters effecting Generator Performance

· Select the generator tab of the simulation.

· In the simulation, controls select the voltmeter to replace the bulb.

You will note that the voltmeter scale is not calibrated, but that you can still compare various potential readings by counting “tick marks” on the face of the meter. Using this scale to collect data, vary the relationship between the maximum electromotive force EMFmax produced and the various parameters in the generator equation, EMF = ωNBAsin(ωt). Specifically, vary the angular frequency (ω) (by adjusting the water flow through the spigot on the left), number of loops (N), and area of the loop (A). Choose one parameter and produce a plot of EMFmax vs. the parameter. Be sure to use at least 10 data points. Record the results in your laboratory notebook.

PART III – Calibrating the Galvanometer

The voltmeter scale is uncalibrated in part because we are missing two values: 1) the average of the peak magnetic field strengths across the surface bounded by the loops in the pickup coil, and 2) the maximum area of the loops of the pickup coil.

Given that the maximum area of the loop is 0.75m², and the maximum magnetic field strength at the location of the coil is 0.6 T, you should be able to find the value of a single tick mark on the voltmeter scale.

In your laboratory notebook write down a detailed procedure for doing so. Carry out this measurement with angular speeds of 25, 50, and 100 RPM. Are these values comparable? Do they need to be for the meter to be useful? Why or why not?

1. The Lab Report

Click here for a lab report template [DOCX file size 12.6 KB], and click here for an explanation of each lab component [DOCX file size 17.4 KB].

· Write an introduction of at least 1 page in length. The introduction should showcase your understanding of electromagnetic induction.

· Write a methods section describing in your own words the experimental procedure used to complete each activity. Do not copy and paste, or simply repeat the directions given in the course materials.

· Write a results section. This section should begin with a paragraph containing any hypotheses formed and tested during the conduct of the laboratory. This section should also contain any data collected, sample calculations, analysis, and plots of the data or results.

· Write your discussion section specifically addressing how your results did or did not support any hypothesis used in this laboratory.

· Write your conclusion. This section should be brief, at most, one or two paragraphs; connect the discussion with the information contained in the introduction.

· Write the abstract. While this is the first section of your lab report, it should be written last. This section should be written in the past tense, in the third person, and should be a summary of the entire laboratory report.

Compose your work using a word processor (or other software as appropriate) and save it frequently to your computer. When you’re ready to submit your work, click Browse My Computer and find your file. Once you’ve located your file click Open and, if successful, the file name will appear under the Attached files heading. Scroll to the bottom of the page, click Submit and you’re done. Be sure to check your work and correct any spelling or grammatical errors before you post it.

You will be evaluated on the validity of your recorded results and the completeness and quality of your presentation of those results within the experiment report, based on the Lab Report Grading Rubric [PDF file size 63.7 KB].