PHYS 2092 Lab 5: Faraday's Law and Lenz's Law INSTRUCTIONS Introduction In this lab, you will explore several predictions of Faraday's Law and the implications of Lenz's Law in Electromagnetism. You will be using an online simulation on the PhET website called Faraday's Law: https:// phet.colorado.edu/sims/html/faradays-law/latest/faradays-law_en.html Theory When a magnetic field B goes through a surface A (may that field be real or imaginary), we say there is a flux @ through the surface. According to Faraday's Law, when a magnetic flux changes through a coil that has /V turns in time t, the rate of change of the magnetic flux generates a voltage &coil at the terminals of the conductor the coil is made of. This average induced voltage can be written as the following: NADB Ecoil =- At (5.1) To figure out the direction of the current through the coil, Lenz's Law is what we need to apply. According to Lenz's Law, when a magnetic flux changes through a coil, the coil generates an induced voltage such that the magnetic field associated with the current through the coil opposes the direction of the change in magnetic flux. We will use a concrete illustration to explain this phenomenon.D Voltmeter C] Field Lines Figure 5.1: Default display ofrhe simulation setup Experiment Launch the PhET simulation provided by the link above. You will have options between 1 coil or 2 coils. 1 C011 system N-S Magnet For the rst part of the experiment, let's keep the 1 coil system. At present, the magnet is displayed as N-S (North to the left and South to the right). Click on the Field Lines checkbox to visualize the magnetic field around the magnet. Click on the Voltmeter checkbox to activate a voltmeter for current ow readings. Describe the direction of the eld lines generated by the magnet in your own words. Now, grab the magnet and slide it through the coil and stop when the magnet reaches halfway through. Describe what you observe. Did the needle move towards the positive or the negative as you are moving the magnet into the coil? Is the current going clockwise (CW) or counterclockwise (CCW)? Now, grab the magnet and slide it out backwards to take it out of the coil. Describe your observations in terms of the needle direction and current directions. How do your observations t with Lenz's Law stated above? 1 Coil system S-N Magnet For the second part of the experiment, we are still keeping the l coil system. Now, click on the small magnet icon located at the bottom right of the simulation panel. This is to flip the polarities of the magnet. Now, you have a S-N Magnet. Now, grab the magnet and slide it through the coil and stop when the magnet reaches halvay through. Describe your observations in terms of the needle direction and current directions. How do your new observations t with Lenz's Law? 2 Coil system N-S Magnet For the third part of the experiment, click on the 2 coil icon to switch to a 2 coil system. Based on Faraday's Law, predict which coil will produce the largest voltage when the magnet passes through each of them at the same speed. ' Now drag the magnet (with N-S polarity), slide it back and forth through the smaller coil and observe the brightness of the lamp. Then, slide the magnet back and forth through the larger coil and compare the brightness of the lamp with what you observed earlier when it went through the smaller coil. Has the increase in the number of coils had any effect on the voltage induced in the coils? Polarity ipping Pick any of the coils and place the magnet halfway through it. Click on the magnet polarity ip several times and describe your observations. What is happening on the voltmeter? What is happening to the lamp? Descriptive Report This lab report is mostly descriptive. Please describe your observations as per the instructions above, onto your Answer Sheet. Conclusions After your observations, how does Faraday's Law and Lenz's Law t in this experiment. Please write your conclusions (for each system) onto your Answer Sheet. PHYS 2092 Lab 5: Faraday's Law and Lenz's Law ANSWER SHEET Student Name: Descriptive Report Please describe your observations below, as per the instructions: 1 Coil system - N-S Magnet Report: 1 Coil system - S-N Magnet Report: 2 Coil system - N-S Magnet Report: Polarity flipping Report:Conclusions After your observations, how does Faraday's Law and Lenz's Law fit in this experiment? 1 Coil system - N-S Magnet Conclusion: 1 Coil system - S-N Magnet Conclusion: 2 Coil system - N-S Magnet Conclusion: Polarity flipping Conclusion