Title of Unit: Energy
Author(s): Julia Heyen
Lesson Plan 18
STATE GOAL 12: Understand the fundamental concepts, principles and
interconnections of the life, physical and earth/space sciences.
Standard C: Know and apply concepts that describe properties of matter and
energy and the interactions between them.
• Differentiate between AC/DC currents and explain usages
Teaching and Learning Event: Investigate AC/DC currents and understand what the
types of currents are used for and where they can be found. Assessment 4; AC/DC
worksheet
Description and Detailed Sequence of Activities:
Teach to Students:
Direct Current (DC)
• The battery we have been using for a current/voltage source generates direct
current, which simply means the current flows in only one direction.
• As long as electrons are flowing through the atoms of the circuit, work is being
done. We can see that work is being done in this circuit because it lights the light
bulb. The actual amount of electrons that are flowing is determined by the type
and size of the battery as well as by the size and type of the light bulb. We could
reverse the polarity of the battery by switching the contacts (wires), and the
current would flow in the opposite direction and the bulb would still light.
• Either way the battery is connected to the circuit, current can only flow in one
direction. Direct current (DC) can also be generated by means other than
batteries. Solar cells, fuel cells, and even some types of generators can provide
DC current.
Alternating Current (AC)
• AC is short for alternating current. This means that the direction of current
flowing in a circuit is constantly being reversed back and forth. This is done with
any type of AC current/voltage source.
• The electrical current in your house is alternating current. This comes from power
plants that are operated by the electric company. Those big wires you see
stretching across the countryside are carrying AC current from the power plants to
the loads, which are in our homes and businesses. The direction of current is
switching back and forth 60 times each second.
•
Spend the second class period going through the electricity activity from the
University of Iowa:
http://www.ndt-ed.org/EducationResources/HighSchool/Electricity/workwithelectricity.htm
•
Finish the lesson by having the students complete Assessment 4; AC/DC
worksheet
Time Line: 2 class periods
Books:
Equipment Name:
Materials: Assessment 4; AC/DC worksheet
Resources - Web Sites:
http://www.ndt-ed.org/EducationResources/HighSchool/Electricity/hs_elec_index.htm
Resources – Software:
TRADEBOOKS ARE INTRODUCED AT THE BEGINNING OF THE UNIT.
THESE BOOKS ARE AVAILABLE AND ACCESSIBLE TO STUDENTS
THROUGHOUT THE UNIT.