{"id":1682,"date":"2015-03-02T10:42:26","date_gmt":"2015-03-02T17:42:26","guid":{"rendered":"http:\/\/sites.evergreen.edu\/motion\/?page_id=1682"},"modified":"2015-03-03T06:34:09","modified_gmt":"2015-03-03T13:34:09","slug":"fields-from-moving-charges-in-class-activity","status":"publish","type":"page","link":"https:\/\/sites.evergreen.edu\/motion\/fields-from-moving-charges-in-class-activity\/","title":{"rendered":"Fields from Moving Charges In Class Activity"},"content":{"rendered":"

(Make sure you are using the Mozilla Firefox browser)<\/p>\n

Part I:<\/strong> Go to Radiating Charge at the PhET Interactive Simulations site http:\/\/phet.colorado.edu\/en\/simulation\/radiating-charge. <\/a><\/strong><\/p>\n

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  1. When you run the simulation, it is as if the positive charge has been created out of nothing. Note particularly that the field lines take a finite amount of time to fill space.<\/li>\n
  2. Click on Linear. Let it run through to the right side of the screen at which point it will start over again coming through the left side of the screen. What do you notice? At some point, click on Stop Charge. What do you notice?<\/li>\n
  3. Change the speed to 0.75c. What do you notice as soon as you make the change? Again, let it run through several times. Compare to 0.5c.<\/li>\n
  4. Change the speed to 0.95c, and again let it run through several times. Compare to previous.<\/li>\n
  5. Press Reset.<\/li>\n
  6. Click on Bump, which moves the positive charge quickly up and back down to its original position. What do you notice?<\/li>\n
  7. Adjust the duration and the amplitude of the bump. What do you notice? In particular, see if the “disturbance in the force<\/a><\/strong>” (I know it should say disturbance in the field but who could resist?) propagates at different speeds or the same speed for different movements of the source charge.<\/li>\n
  8. Press Reset.<\/li>\n
  9. Click on Manual, which lets you move the charge however you wish using the mouse. Move the charge quickly up and down (this reproduces Bump). Now, move the charge side to side. Compare both cases, in particular, to see if there is any direction where no disturbance propagates. Also, in what direction (compared to the charge motion) is the disturbance greatest? Try moving back and forth along some of the other field lines (the diagonal ones).<\/li>\n
  10. Press Reset.<\/li>\n
  11. Click on Sinusoidal and observe. Adjust the amplitude and frequency. What effects do those have?<\/li>\n
  12. Press Reset.<\/li>\n
  13. Click on Circular and observe. Adjust the amplitude and frequency. Compare to Sinusoidal.<\/li>\n<\/ol>\n

    Part II:<\/strong> Go to Radio Waves & Electromagnetic Fields, also at PhET. You’ll have to accept several prompts to Run, go ahead and do so. http:\/\/phet.colorado.edu\/en\/simulation\/radio-waves<\/a><\/strong>.<\/p>\n

      \n
    1. Under Field Sense, click on Electric field. In Field Displayed, click on Static field.<\/li>\n
    2. Use the mouse to wiggle the electron in the KPhet antenna.<\/li>\n
    3. Click on Oscillate. Watch the electron in the receiving antenna on the right (you might need to wait a bit). What do you notice? Click back on Manual so that the antenna electron stops. Watch the receiving electron – again wait a bit, what do you notice?<\/li>\n
    4. In Field Displayed, click on Radiated field. Make sure that Field Display Type is on Full Field. Make sure you are on Manual, and wiggle the electron. What do you notice? How does this connect with what you did\/saw in Radiating Charge? What happens when the disturbance reaches the receiving electron?<\/li>\n
    5. Click on Oscillate and observe.<\/li>\n
    6. Under Field Display Type, click on Curve with vectors. What do you observe?<\/li>\n
    7. Play around with Frequency and Amplitude. In addition to the effect on the Radiated field, pay attention to the effect on the receiving electron.<\/li>\n<\/ol>\n

      Part III:<\/strong> Go to http:\/\/www.falstad.com\/mathphysics.html<\/a><\/strong> and scroll down to Electrodynamics.<\/p>\n

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      1. \u00a0Launch the 2-D Electrodynamics Applet (TE). Note: it might open in another browser window, so look for it in the background or behind another window.<\/li>\n
      2. Under Setup, choose Oscillating Dipole (you’ll need to scroll up). Choose Show E lines. Use the scroll bar to slow down the Simulation Speed (but not to zero), and increase the Resolution a bit.<\/li>\n
      3. This is quite complex, so play around with various settings like brightness, frequency, etc. Show different E, B, etc.<\/li>\n
      4. See what sense you can make with some open-ended investigation.<\/li>\n
      5. If interested, you can explore the 2-D Electrodynamics Applet (TM) which in contrast to the previous version, has sources that primarily work by varying Magnetic fields.<\/li>\n<\/ol>\n

        Part IV: <\/strong>Go to Chapter 32: Optics at the Physlet Physics site of compadre.org http:\/\/www.compadre.org\/Physlets\/optics\/intro32.cfm<\/a><\/strong>. You may need to accept some prompts to Run; go ahead and do so.<\/p>\n

          \n
        1. You have already completed the equivalent of Illustration 32.1: Creation of Electromagnetic Waves in Part I of this activity. You may find the text description helpful.<\/li>\n
        2. Read through and complete Illustration 32.2: Wave Crests.<\/li>\n
        3. Read through and complete Illustration 32.3: Electromagnetic Plane Waves. Note: click-drag inside the large panel before starting the animation. Also, the last paragraph defines some symbols.<\/li>\n
        4. Read through and complete Illustration 32.4: Electromagnetic Waves, E <\/strong>x B<\/strong>. Pay particular attention to the last paragraph.<\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"

          (Make sure you are using the Mozilla Firefox browser) Part I: Go to Radiating Charge at the PhET Interactive Simulations site http:\/\/phet.colorado.edu\/en\/simulation\/radiating-charge. When you run the simulation, it is as if the positive charge has been created out of nothing. … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":219,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"onecolumn-page.php","meta":{"_mi_skip_tracking":false,"_s2mail":"no"},"_links":{"self":[{"href":"https:\/\/sites.evergreen.edu\/motion\/wp-json\/wp\/v2\/pages\/1682"}],"collection":[{"href":"https:\/\/sites.evergreen.edu\/motion\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/sites.evergreen.edu\/motion\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/sites.evergreen.edu\/motion\/wp-json\/wp\/v2\/users\/219"}],"replies":[{"embeddable":true,"href":"https:\/\/sites.evergreen.edu\/motion\/wp-json\/wp\/v2\/comments?post=1682"}],"version-history":[{"count":0,"href":"https:\/\/sites.evergreen.edu\/motion\/wp-json\/wp\/v2\/pages\/1682\/revisions"}],"wp:attachment":[{"href":"https:\/\/sites.evergreen.edu\/motion\/wp-json\/wp\/v2\/media?parent=1682"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}