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.
Here are some things to do to finish this section.
What question did you think of that could be studied, or
observation could you make that is interesting or unexpected?
Send it to the Question board!
Discuss these questions with the people in your group. Please
send us a discussion of these four
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!).
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?
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.
What
is the water equivalent of
a capacitor? Where around the house do we have a "water capacitor"? Give
a water analogy to the previous question (using a capacitor to light the
light bulb, when the battery we made can't do it by itself).
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 ) The next section is about resistance
Here are some other pages you might like to look at sometime: