BACKGROUND:
There are 2 basic kinds of
electricity: static electricity and current electricity. Static
electricity is uncontrolled electrons passing from one body to another
in sudden, momentary movements. Examples include clothes from the dryer
that stick together; or getting a shock after walking on a carpet and
then touching something. Static electricity is usually a nuisance and a
hazard that can cause fires.
Current electricity is when the
electrons are controlled by moving along a path together. The path is
usually a conductor of electricity. A copper wire can move electricity
from a power plant to a house.
PROCEDURE:
-
Static electricity
can be illustrated by showing students the plasma ball. Plasma is
stripped electrons, which is basically what static electricity is. In
many plasma balls, the plasma gives off a light different than most
static electricity we are used to. Demonstrate the different ways you
can control some of the electrons by putting your hand to the ball. This
demonstration looks better in a dark room. Put a small fluorescent tube
to the Plasma Ball. Notice that the electrons will light the tube. The
electrons go through the tube and excite the gas to give a glow.
The electricity is
always looking for the "ground." So it uses your body to
conduct the electricity. However, it is not enough electricity to cause
any harm.
-
Current
electricity is controlled; the electrons all move in one direction. Wire
can transmit electricity so it becomes a very useful energy source. When
its movement along a wire is controlled, it is current electricity.
Remember, electricity is a flow of electrons in one direction.
-
On the board, have
students make a list of their experience with electricity. Put it in 2
columns - CONTROLLED (CURRENT) and UNCONTROLLED (STATIC), as illustrated
below. Students are sure to bring up lightning which is a visible
discharge of electricity. This will be explained in the post lab.
CONTROLLED |
UNCONTROLLED |
electric circuit
electric oven
electric can opener
|
when clothes get stuck
when socks stick to clothes
when confetti gets stuck on items
|