Lightning in a Pan

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Lightning in a Pan

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 here.

Materials

• Aluminum pie plate
• Ball-point pen
• Thumb tack
• Wool sock
• Piece of styrofoam

Instructions

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.

What’s Happening

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.

Candy Lightning

Make lightning—in 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 it’s 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 candy’s wintergreen flavouring absorbs the UV radiation and re-emits it as the spark you can see. It’s science—in your mouth. Try it!

Prove 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 storm is.