Students were taught to explore how current electricity travels in
pathways called circuits.
Students taught to create a working circuit using a light
bulb, battery, two types of switches, and wire.
• I can define the terms “circuit” and “current electricity”
and tell you where we used them in everyday life.
• I can describe the difference between closed, open, and
short circuits as applied to real life situations.
• I can show you how a switch works and why switches are
important.
• I can explain electrical insulator and conductor and give
several examples of each. Background Like static electricity, current
electricity involves the movement of electrons.
The difference is that in current electricity electrons move
from atom to atom along a pathway called a circuit. To create a circuit you
need wire, an electrical source such as a battery, and a load (the item you
want to work such as a light bulb or motor).
The electricity must be able to move from one end of the
electrical source (the battery, turbine generator or photovoltaic panel) to the
load and back to the electrical source to create a complete circuit.
Electricity taught to only do work (example: light the bulb or run a motor)
when it is complete or closed.
In a closed-circuit
electron are able to travel the entire pathway (loop) without hindrance via
materials that conduct electricity. In an open circuit, there is a disruption
in the pathway caused by a break in the loop because of the absence of material
that can easily conduct electricity.
Thus, electrons are unable to move through these locations
and make a complete circuit. You can think of an open circuit as a toy train
track assembled to form a circle with a piece of track missing.
As the train, (think of it as electrons), moves along the
track it derails at the missing track piece and cannot complete the circle
(circuit). A short circuit is when there is a complete circuit or loop, but the
flow of electrons takes a “short-cut” bypassing the load.
Short circuits happen when the wiring of a circuit is faulty
and does not form a pathway that must pass through the load as seen in class
lessons
Current Electricity –
Circuits and Switches.
If the circuit is shorted, the load will not work. For
example, if the load is a bulb it will not light because it is not receiving
the electricity (electrons). The wires we will be using are made of copper or
aluminum, which are conductors (they readily transmit electricity). The wire is
coated with plastic; an insulator (does not allow any significant flow of
electrical current).
Everyday materials are divided into two groups: conductors
and insulators. Most metals like copper, aluminum, iron, zinc and steel are
conductors. Water is also a fairly good conductor, especially if it contains
minerals and/or electrolytes. Insulating materials include rubber, plastic,
glass, and wood.
The electricity will flow from the electrical source
(battery) through the wires to the load (light bulb).
In everyday use of electricity, humans use switches to turn
on and off the flow of electricity to electrical devices. The switch is an
important part of the circuit even though it is a simple concept.
The switch in a circuit merely allows one to open or close
the circuit, controlling the flow of electrons along the pathway. If one turns
the switch on, the switch closes the circuit allowing electricity to flow.
Turn the switch off and it opens the circuit – electrons
can’t cross the tiny space created inside the switch.
The three kinds of switches provided in the following
activity taught to allow students to explore the way “on” switches allow a
closed circuit to be created and “off” switches allow an open circuit to be
created.