Written Assignment #5 – Model Of An Electric Generator

Written Assignment #5 – Model of an Electric Generator Group Members: Please enter the names of all of the members of your group, whether they participated in this activity or not. Later on, you9ll have a chance to identify any group member who may not have participated. Information: These questions are a modified version of Question 5 from Class 27 in the course packet. It is recommended that you work through the questions on the worksheet while answering the following questions. You will need to use the PhET: Faraday’s Electromagnetic Lab. This PhET runs in a browser, or as a separate java file. You9ll find instructions below on how to grab the file.. · Each group member should be the primary contributor/writer for at least 2 of the question parts of this assignment. · Please enter your answers directly in this file, and submit the completed file through d2l. Enter name of primary group contributor for this question part: 5. Open the University of Colorado PhET: Faraday’s Electromagnetic Lab (NOTE: This is different from the Faraday9s Law PhET). Here are your options for finding and using the PhET: · From Week 07 of the Contents page, click on the link that will run Faraday’s Electromagnetic Lab inside your browser. If it seems slow, you might try a different browser. This link is also available from the Simulations widget on the main course d2l page. · If you have java on your laptop or computer, go to the Simulations widget on the main course d2l page, and download the PhET as a java file. · Do a web search for 8cheerpj phet faraday9 and you will probably find the link to run the PhET in your browser, but option 1 (above) is the safer choice. The simulation will open up with the Bar Magnet option. Choose the Generator tab on the top. You should then see the window below (but with a black background). A. [4 points] In the settings on the right, turn the Show Field option ON (to show the magnetic field), and switch from the light bulb to the meter indicator. Then turn on the water flow so that the bar magnet rotates at about 50 rpm (revolutions per minute). i. Please use physics concepts and terminology to explain (in 2-3 sentences) why the rotating magnet produces a current in the light bulb or current meter. The rotating current produces a current in the current meter through electromagnetic induction which is explained partially by Faraday's law. The changing magnetic flux caused by the rotating wheel results in a sort of push and pull of the electrons creating an electric current. ii. In 2-3 sentences, please explain why the current in the coil changes directions. Since the magnet is rotating in a circle, the push and pull of the opposite poles (negative and positive) causes a change in the direction of the current due to the fact that negative and positive charges have opposite facing magnetic fields. (also seen when using the right hand rule) B. [4 points] Identify 4 different adjustments you can make to increase the maximum current induced in the light bulb loops (coil). 1) 2) 3) 4) Increase the water being let out, so increase the RPM. Increase the loop area Increase the number of loops Increase the strength of the bar magnet C. [4 points] Faraday’s law is an extension of Lenz9s law, and says that the induced current in a loop or coil of wire is proportional to the rate of change of the magnetic flux through (or inside) that loop or coil. Use Faraday9s law and concepts from Lenz9s law to explain why each of your 4 adjustments increase the maximum induced current. HINT: You9ll want to use the definition of flux in your explanations. Please include a separate explanation for each of the 4 adjustments you identified in Part B. 1. Increase the water being let out, so increase the RPM. a. Flux can be defined as the action or process of flowing in or flowing out (flux = NAB), so when you increase the flux of the water you are directly increasing the magnetic flux through the coil in the same amount of time. 2. Increase the loop area a. Increasing the loop area increases the induced current because the flux is NAB, which includes the area (A). A and I are directly proportional to one another so when the loop area increases, the induced current will increase as well. 3. Increase the number of loops a. Flux is equivalent to N*A*B. As the number of loops increases (N), the flux increases because they are directly proportional. This means the induced current will also increase. 4. Increase the strength of the bar magnet a. Flux is equivalent to N*A*B. As the strength of the bar magnet (B) increases, the flux also increases because they are directly proportional. This means the induced current will also increase. D. [3 points] Change your settings so that: · · · · The water flow has the bar magnet rotating at about 60 rpm The bar magnet strength is set to 100% The light bulb/meter coil has 3 loops, and The loop area is set to 100%. Assume that the voltmeter indicator has settings of 5 V for each major division. You should find that the maximum voltage is about 15 V. Based on your observations for the voltmeter, sketch a prediction for the corresponding voltage vs. time graph. NOTE: You9ll add to this same graph when answering Part E. Options for your sketch, you may: § take a picture of a sketch and insert the picture in this Word document, OR § attach a separate picture file in the Submissions folder AND identify the file name below, OR § draw on the axes below using Word (Insert > Shapes > Curve or Freeform line). There have been some issues seeing and/or editing the figure below, so adding a picture may be the better option. E. [4 points] Properties of the voltage vs time graph. i. Is the voltage periodic? If so, how do you know that it is periodic, and what is the numeric value of the period? Yes, the voltage is periodic. You can see this because the voltage meter goes from the maximum value and very quickly over zero and back to the maximum value but with a negative number. The magnitudes of the two maximums are the same. The period is one second. ii. What is the numerical value of the amplitude? 15 V iii. Go back to your predicted graph and label the x- and y-axes of your graph (with numbers) based on your answers to questions i and ii.