Lightning is beautiful, dangerous,
and mysterious. The same brilliant flashes that inspire poetry
and paintings can cause city-wide power outages and raging forest
fires. While the average lightning bolt is only about five kilometres
long and the width of a finger, it heats the surrounding air to
a temperature five times hotter than the surface of the Sun and
produces enough energy to power a 100 watt light bulb for three
months. Try this easy experiment to make your own miniature version
of a lightning bolt.
For a printable version of this project, click
|• Aluminum pie plate
• Ball-point pen
• Thumb tack
• Wool sock
• Piece of styrofoam
|1. Push the thumb
tack up through the centre of the pie plate.
2. Push the end of the pen onto the tack. Secure
it with glue if necessary.
3. Rub the styrofoam quickly with the wool sock.
4. Pick up the aluminum pie plate with the pen
and put it down on top of the styrofoam. Be sure not to touch the
pie plate with your hands.
5. Turn out the lights and slowly bring your finger
close to the pie plate. You should hear, feel, and see a tiny spark.
|As you rub the styrofoam, it steals
electrons from the wool and becomes negatively charged. Because
like charges repel (move apart) and opposite charges attract (move
together), the excess electrons on the styrofoam repel the electrons
on the pie plate and push them to the top edge of the plate. The
pen acts as an insulator, preventing the built-up charge from moving
through you to the ground until you are ready. When you bring your
finger close to the edge of the plate, the repelled electrons jump
across the gap and escape through your body, giving you a small
shock. When you turn off the lights, you should be able to see (as
well as hear and feel) the discharge.
|Make lightningin your mouth.
Go into a dark room and chew up a few Wint-O-Green LifeSavers while
looking in the mirror. (This is one time when its okay to
chew with your mouth open!) Can you see the flashes in your mouth?
Crunching the candy breaks the sugar crystals and builds up opposite
electrical charges on the pieces. Electrons jump between the pieces,
colliding with nitrogen molecules to make invisible ultraviolet
(UV) radiation. The candys wintergreen flavouring absorbs
the UV radiation and re-emits it as the spark you can see. Its
sciencein your mouth. Try it!
|Crash! Flash! The lightning looms
then the thunder booms. Thunder and lightning both happen at the
same time. We see lightning before we hear thunder because light
travels much faster (300,000 km/sec) than sound (.3 km/sec). Just
how far away is that noisy storm? Count the number of seconds between
seeing the lightning and hearing the thunder. Divide this number
by three to get a rough estimate of how many kilometres away the