Complab6-magnetic-effects.doc

General Physics 2 Lab - PHY 2049L Lab 6: Electromagnetic Induction

Name __________________________ Date ________________

Simulation: Play with Simulations: Simulation A: Magnets and Electromagnets http://phet.colorado.edu/en/simulation/magnets-and-electromagnets Part I – Virtual Lab Experiment: 1. Move the compass slowly along a semicircular path above the bar magnet until you’ve put it on the opposite side of the bar magnet. Describe what happens to the compass needle. 2. What do you suppose the compass needles drawn all over the screen tell you? 3. Click on the electromagnet tab. Place the compass on the left side of the coil so that the compass center lies along the axis of the coil. (The y-component of the magnetic field is zero along the axis of the coil.) 4. Move the compass along a semicircular path above the coil until you’ve put it on the opposite side of the coil. Describe what happens to the compass needle. 5. Move the compass along a semicircular path below the coil until you’ve put it on the opposite side of the coil. Describe what happens to the compass needle. 6. Use the voltage slider to change the direction of the current and repeat the steps above for the coil after you’ve let the compass stabilize. 7. Based on your observations, summarize the similarities between the bar magnet and the coil. 8. What happens to the current in the coil when you set the voltage of the battery to zero? 9. What happens to the magnetic field around the coil when you set the voltage of the battery to zero? 10. Play with the voltage slider and describe what happens to the current in the coil and the magnetic field around the coil. Part II – Graphing relationships: Field Strength vs. Position 1. Using the Electromagnet simulation, click on “Show Field Meter.” 2. Set the battery voltage to 10V where the positive is on the right of the battery. 3. Along the axis of the coil and at the center of each compass needle starting 5 to the left of the coil, record the value of B. Move one compass needle to the right and record the value of B. Repeat until you’ve completed the table below. NOTE: Be sure to take all of your values along the axis of

the coil. You’ll know you’re on the axis because the y component of the magnetic field is zero along the axis. Compass position (arbitrary units) -5 -4 -3 -2 -1 0 1 2 3 4 5

Magnetic Field Strength (fill in units)

Simulation B: Faraday’s Law http://phet.colorado.edu/en/simulation/faradays-law Faraday’s Electromagnetic Lab http://phet.colorado.edu/en/simulation/faraday Pickup Coil Tab – General Electromagnetic Induction 1. Set the number of loops to “1” and note what happens to the light bulb when The magnet is not moving and is not in the loop – The magnet is moving and is not in the loop – The magnet is not moving and is in the loop – The magnet is moving and is in the loop 2. Does the speed of the magnet affect your results to #3? If so, describe how. 3. Increase the number of loops to “3” and see if it affects your results from #3. If so, describe how. 4. Increase the loop area to “100” and see if it affects your results from #3. If so, describe how.

Pre-Lab Use the computer simulation ‘Generator’ here to answer these questions and submit your answers online. Simulation C: Generator http://phet.colorado.edu/en/simulation/generator Bar Magnet 1. How does the simulation indicate which direction the magnetic field points? 2. Click “Show Field Meter.” Using the magnetic field strength “B,” compare the strength of the field at the poles and at the side of the magnet. Which is larger? Pickup Coil 1. How can you make the lightbulb light up? 2. What happens to the direction of the current when you move the magnet back and forth? 3. Click on the voltage indicator. What happens as you move the magnet from the left of the coil to the right? 4. How does changing the number of loops affect the voltage when you move the magnet? Electromagnet 1. What happens to the magnetic field as you adjust the number of loops? 2. What happens to the magnetic field when you switch to AC voltage? Transformer What five things can you adjust to get the highest maximum voltage? Generator What four things can you adjust to get the highest maximum voltage?