Making sparks fly
Do sparks fly when you pull your jacket off?
Do you get a crackling shock when you touch a doorknob? These things
happen because you’ve been collecting electricity!
The sparks and crackles are static [(stat]{.smallcaps} ihk)
electricity—electrons that pile up in one place. On cool, dry days,
you collect electrons very easily. You actually scrape them loose from
things! When you walk across a rug, or
when your jacket rubs against you, the loose
electrons stick to your body.
The loose electrons can’t flow through you the way they flow through a
wire. But they can jump from you to a kind of material that has fewer
electrons. So, when you reach for the doorknob or pull off your jacket,
that’s exactly what happens. Then you hear the crackle of electrons
jumping from place to place—and sometimes you feel it, too!
A moving electron show
Would you like to see the pull and push electrons make? You can do it
with static electricity you collect on a balloon.
Materials
balloons (2)
string
wool cloth
Blow up both balloons and tie strings to them. Rub one balloon with the
cloth. Then touch the balloon to the cloth and let go of the string.
What happens?
Rub both balloons with the cloth. Hang the balloons next to each
other. What happens this time?
When you rub the balloons, they pick up electrons from the cloth. The
balloons then have more electrons than the cloth.
When you put a balloon next to the cloth, the piled-up electrons on the
balloon begin to move back to the cloth. They make a pull that sticks
the balloon to the cloth.
But when you put the two balloons together, the piled-up electrons have
nowhere to go. Both balloons have too many electrons, so they push each
other away.
