Discussion of the section on concepts of electricity

Each section in this Hands-On / Virtual workshop ends with a discussion page.  The questions we ask here serve two important purposes.  First, they help your group reflect on the concepts that you have studied in this section, summarize what you have learned, and encourage you to connect those concepts to other things you experience in the world.  Secondly, they are the means by which the remote instructors of the class get immediate feedback on how much the group is thinking and learning.  They are the immediate section assessment.

You are asked as a group to discuss at least 2 of the following questions.  We encourage you to discuss them all, but we ask for an email commentary to only two of them.  Before you start please see this page for some guidance on what types of discussion we are looking for.  After you email your discussion, you can expect (within a day or two) an email from us commenting on what you wrote. Sometimes this commentary will ask for further discussion; sometimes it will give examples of what other groups had to say. You should always read these commentaries carefully, and reply to the follow-up questions if there are any. These comments are intended to guide you to a better understanding of the subject matter.

Here are some things to do to finish this section.

Discuss these questions with the people in your group. Please send us a discussion of these three questions. Don't forget to tell us the group name. (Clicking on the link should start your email program, and fill in the address automatically. However, sometimes this does not work, or causes the wrong email program to be started. If the email link does not work for you, send the messages the way you are used to, to sciworks@pa.uky.edu -- or reply to a message from us!).
  1. Some batteries are rechargeable (for example, the one in your car). How is a rechargeable battery similar to a capacitor, and how is it different -- of course they are different inside, but what differences in behavior are there?

    When the capacitor is charged to 3 V, it contains about 1 Joule (equivalent to lifting an egg 1 m). You can use your observations to determine the power rating for a flashlight light bulb. Power (in watts) is the amount of energy divided by the time spent releasing it. So divide 1 Joule by how long the capacitor can keep the light bulb glowing, to find the power. Then use the relationship between current, voltage, and power to estimate how much current it takes to light the light bulb.

    How many charged capacitors would we need to replace one flashlight battery?
  2. The battery we made could light a LED, but could not produce energy fast enough to light a light bulb. Could we charge the capacitor with the home-made battery, and then use it to light the light bulb? Discuss what you would have to do to make this work.
  3. In the first module we frequently compared fluid systems to electrical systems. Construct a water analogy to explain why the home-made battery could light the LED but not a light bulb. For example, "getting the light bulb to work" could be represented by "getting enough flow rate to take a decent shower" -- but then what are the equivalents for the battery that won't light the light bulb, and the light emitting diode that does work? We could continue the analogy to discuss the previous question: what is the water equivalent of the capacitor? What does the analogy tell us about the previous question?

If there is something that you don't understand about the basic concepts of electricity, Ask us!

This is the end of this section. (Check this box check box )   The next section is about resistance

Here are some other pages you might like to look at sometime: