Lab 10-2 2
.pdf
School
California State University, San Marcos**We aren't endorsed by this school
Course
GES 110
Subject
Physics
Date
Jan 10, 2025
Pages
4
Uploaded by BailiffEagleMaster1213
Electromagnetic Induction Part 2Brandon Castro10-2BackgroundWhen a magnet is stationary it produces a constant magnetic field around it; but if the magnetis moving, the magnetic field around it changes. Michael Faraday in the first half of 19th centuryextensively studied the changes in magnetic fields. He discovered thata changing magneticfield induces a voltage and current in a nearby conductor. Lenz’s law explains thedirection ofthe induced current.Part 2You know that a compass is an instrument that indicates the presence of a magnetic field. It willalign itself in the direction of the field lines. A bar magnet is a simple device to produce a smallmagnetic field in a region. In this simulation if there is a magnetic field in the background, thefield lines in that region are depicted by tiny compass needles. A changing magnetic field isseen as the compass needle moves.In part 2 of the lab we review how electromagnets, transformers and generators work.Gotohttps://phet.colorado.edu/en/simulation/faradayand open the Java CheerpJ PhET Faraday’s EMI Lab.PROCEDURE:1. Start with theBAR MAGNETtab. Use the settings shown.Keep the strength of the magnetat 100% and notice thebackgroundas well as thereadingin thefield meter. Gradually reducethe magnet strength to 50% and finally to 0% and observe the same in each case. Comment onyour observations.2. Bring the field strength of the magnet back to 100%. Flip the polarity by clicking on the button.Pause, and observe. Do this a few times. Write down your observations:3. Go to thePICKUP COILtab. Keep the settings as shown in figure 4. Arrange the magnet,field meter, and coil as shown in the figure.
Move the field meter slowly to the right ALONG A STRAIGHT LINE. Record values at threedifferent positions as youmove the coil awayfrom the magnet. You can infer about themagnetic field from this: _______A.The magnetic field stays a constant in the space aroundB.The magnetic field changes in the space aroundC. The magnetic field does not exist around the magnet4. a. Faraday’s Law says:4.b. Now take the meter away and bring the loop up to the magnet. As you move the loop swiftlyaway and towards the magnet in a straight line, what do you observe.Explain why this happensbased on Faraday’s law. (DO NOT MOVE THE MAGNET)5. Move to the next tab –ELECTROMAGNET.Use the setting shown in figure 6. The knob onthe battery can vary the battery voltage. Keep the knob at 10V as shown. Observe the compassand the magnetic field around and current in coil.Next slowly slide the knob to the other endwhere it will show 10v again.Summarize what changed(a) in the backgroundb) in the coil(c) and in the compass?6. Click on AC in the right-side panel. The coil is now connected to an AC current supply. Varythefrequencyby adjusting the HORIZONTAL slider knob. (Keep the vertical slider at 100% foramplitude.) Observe the background, the compass, and the field meter as vary the frequencyset at 25%, 50% and 100%. Comment on your observations.As the frequency of the ac current is increased you observe thatCompass:
Field Meter:Background:7. So what do you think is the advantage of connecting an AC source to the coil rather than aDC battery?(note: we are studying magnetism here so think about the magnetic field)Move to the next tab:TRANSFORMER. Adjust settings to those shown in figure 7.8. Get the bulb to light up (Current is induced in that coil) and explainhowyou did it and exactlywhyit lit up.9. Next click on AC so that the primary coil is replaced by an ac source. Keep the two sliderknobs on the ac source at 100%.a)How do you get the bulb to light up. Did you move anything?b)Was it more efficient to do than in #9?c) Explain the advantage of using an AC source to the primary coil.
10. Move to theGENERATORtab. Use the settings shown in figure 8. Turn on the faucet all theway so that the wheel rotates at 100RPM. What do you observe? Explain why electricity isbeing generated in the coil/bulb.11. Observe the brightness of the bulb as you vary the following parameters andexplain whathappens –how brightness changes:a) Vary the RPM (rotation of wheel) by adjusting the flow of water:b) Change the # of loops of the coil:c) Change the strength of the magnet: