Ch22_Demberro

toc =Chapter 22=

Virtual Lab
Purpose: What happens during electromagnetic induction?

Hypothesis: v What conditions are required to induce a current in a loop of wire? There must be a change in magnetic flux. v What factors influence the direction and magnitude of the induced current? Due to the fact that Φ m=BAcosø, if magnetic field, area, or angle between the two, there shall be a change in magnitude and direction.

Procedure:
 * 1)  You can find the virtual lab at  [].


 * 1)  On the left side of the screen scroll down and click on the Electricity, Magnets & Circuits link. Click on the virtual lab called “Faraday’s Electromagnetic Lab.” It should automatically download and open on your computer.


 * 1)  Prepare an observation table. You need two wide columns, labeled //Experiment// and //Observation//. For each part of the lab you will write a brief description of what you do in each step under //Experiment//. In the //Observation// column, record your observations.


 * 1) ** Induction With a Permanent Magnet ** : Click on tab called //Pickup Coil//.
 * 2)  In the middle of the right side of the screen click on voltage meter to switch the indicator on the coils from a light bulb to a voltage meter. Also click on the button that displays all charges.


 * 1)  Click and drag the coil over the north pole of the magnet. Observe the voltage meter and the green dots that represent electrons in the coil.


 * 1)  Repeat moving the coil more slowly. Observe the voltage meter. Record your observations in your Observation Table.


 * 1)  Repeat Steps b and c, moving the coil over the south pole of the magnet. Observe the voltage meter.


 * 1)  Now click on the magnet. Quickly move the north pole of the magnet in and out of the coil. Repeat slowly. Move the magnet to the other side of the coil and repeat this step using the south pole. Observe the meter.


 * 1) ** Induction With an Electromagnet: ** Click on tab called //Transformer//.
 * 2)  In the middle of the right side of the screen click on voltage meter to switch the indicator on the coils from a light bulb to a voltage meter. Also click on the button that displays all charges.


 * 1)  Move the smaller coil inside the larger coil. Observe the voltmeter and the green dots that represent electrons in the larger coil. Record your observations in your Observation Table.
 * 1)  Decrease the current in the smaller coil, by moving the slider on the battery to the left until it reads 5 V. Repeat Step b.


 * 1)  Reverse the current in the smaller coil, by moving the slider on the battery all the way to the left. Repeat Step b.


 * 1)  Replace the DC battery with AC power supply, by clicking on the AC button in the box labeled Current Source on the top right side of the screen. Repeat Step b.
 * 1)  Increase the magnitude of the power supply by moving the slider on the left side of the power supply up. Repeat Step b.

Observations: Discussion: v Based on your observations from the first part of the lab, did the speed of the motion have any effect on the galvanometer? Yes, as shown from the observations, faster speeds led to more movement on the galvanometer.
 * Experiment || Observations ||
 * Drag coil over north end of the magnet. || Voltage meter moves significantly to the left for a millisecond. Electrons move at same rate. ||
 * Drag coil slowly over north end of the magnet. || The voltage meter quickly goes a little to the negative side then stutters and goes back to the middle after a millisecond moving. Electrons move at same rate ||
 * Drag coil over south end of the magnet. || Voltage meter moves significantly to the positive side for a millisecond. Electrons move at same rate. ||
 * Drag coil slowly over the south end of the magnet. || Voltage meter quickly goes to positive sides, stutters, then goes back to middle. Electrons move at same rate. ||
 * Quickly move north side in and out. || Going in one way, voltage meter quickly goes to positive side, then equal distance to the negative side. Electrons go one way when magnet goes in, then opposite way coming out. ||
 * Slowly move north side in and out. || Slowly stutters to positive side, then goes middle, then to negative side on the voltage meter. Electrons go one way, stop, then go opposite direction, on pace where the magnet goes. ||
 * Quickly move south side in and out. || Going in, voltage meter quickly goes to negative side, then equal distance to positive side. Electrons move one was going in, the other going out. ||
 * Slowly move south side in and out. || Slowly stutters to negative side, then to middle, then to positive side on the voltage meter. Electrons slowly go one way, stop, then go other way as magnet goes. ||
 * Transformer Part ||  ||
 * Move small coil of battery inside bigger coil of voltage meter. || Voltage meter goes to the left side, then stops. The electrons move one direction then stop at same time voltage meter does. ||
 * Repeat prior step with half the voltages. || Same thing as before, only things moved much less. ||
 * Same as first step for this part, only charge on other side. || Same as first step of this part, only in reverse. ||
 * Move small coil of AC inside bigger coil of voltage meter. || Both the arrow on the volt meter and the electrons on the coil oscillate back and forth between both directions, an equal distance. ||
 * Repeat prior step with voltage doubled. || Same thing as before only with a bigger magnitude. ||

v In the first part of the lab, did it make any difference whether the coil or the magnet moved? No, the effect was the same.

v Explain what the voltage meter readings revealed to you about the magnet and the wire coil. The voltage meter gives a //qualitative// depiction of how much charge there is and which direction magnetic field is moving relative to other movements and another direction.

v Based on your observations, what conditions are required to induce a current in a circuit? A magnet or current moving through something so the magnetic field can act on something.

v Based on your observations, what factors influence the direction and magnitude of the induced current? Magnetic field, angle between magnetic field and area, and area.

Conclusion: My hypothesis was correct. As shown in my observations, the change in the voltage meter came when the electrons moved, showing that magnetic flux needs a change in magnetic field, which occurred when the magnet or ring would pass through the voltage meter. Furthermore, the needle in the voltage meter moved more when there was a higher voltage in the battery/AC because voltage is directly related to current, which is directly related to magnetic field strength. Also, the direction of the induced current is all relative, yet it comes from entering either the north or south side of the magnetic field. This lab is important to understand since it will lead to better understanding magnetic flux, which can help when discovering the effect of Earth's magnetic field on normal occurrences.

Guiding Questions 4-17