In ESP's Electrical Circuits unit, students learn
about parallel and series circuits, about solid and liquid conductors of
electricity, and about resistance. Carbon dry cell batteries are
provided as alkaline batteries can cause burns when used in low
resistance circuits. All batteries are tested before being sent out with
the unit but, since they do not have a long shelf life, some may go
dead. Please contact ESP if you need additional batteries.
testing of conductivity of liquids can be a challenge. Follow the
directions carefully, using 4 batteries in series. Put a Fahnestock clip
at the end of each wire. Hold the clips close together in the liquid
with the broad, flat sides facing each other. Make sure you have a #40
bulb. The lower resistance of the #41 bulb will probably not light in
this circuit. Current moving through the liquid can be detected two
ways: the bulb may light or bubbles may form on the Fahnestock clips as
water is split into its component oxygen and hydrogen. If the bulb will
not light, try another #40 bulb, the resistance in the bulb you are
using might be too low. While tap water will not conduct electricity
well enough at 6 volts of direct current from 4 batteries, remember that
house current is a different situation. Be safe, never use an electrical appliance which uses house current in a wet environment!
The Electric Universe
is a Web site with a variety of resources on electricity including
safety tips and the biographies of a few of the major figures in the
development of electricity. The site includes Louie's Space for elementary students.
The Energizer Battery Company's site explains how dry cell batteries work. You can make your own, weak battery using a lemon and some other supplies.
The Franklin Institute's page Franklin...He's Electric tells a little about America's first famous explorer of things electric.
For some recommended books for students and teachers, see our book list for Electrical Circuits (see left navigation).
Electricity is one form of energy. A unit on electrical circuits can be part of a super unit about energy. Energy Quest is a very useful Web site for students exploring energy concepts.