Summary Make small sparks with static electricity. Can be used to model lightning. Science content Physics: Electricity, Electromagnetism (7) Earth/Space: Weather, Seasons, Climate Change (K, 1, 4, 7) Lessons activity is in Static electricity Weather phenomena Weather Weather and Seasons Materials aluminium pie plate with styrofoam handle, so it can be picked up without touching the metal (see first photo) flat of styrofoam or foam, that picks up a charge when rubbed on hair Procedure Rub the bottom of the styrofoam/foam block on your hair. (Electrons transfer from your hair to the styrofoam, giving the styrofoam a negative charge.) Drop the styrofoam upside down on a table or on the floor, so the negatively-charged surface is now up. Use the handle to pick up the pie tin, then drop it onto styrofoam - do not touch the pie tin or styrofoam. (Electrons in the pie tin move away from the negatively-charged surface of the styrofoam, and so cluster on the top side of the pie tin.) Very slowly bring the tip of your finger towards the pie tin. You should feel a tiny spark when your finger is very close, but not touching. (Electrons jump from the pie tin to your finger, to get away from the negative charge of the excess styrofoam electrons.) This spark is static electricity. Lighting is also static electricity, but with much more energy. The pie tin is now short of electrons. Use the handle to pick up the pie tin again (so this charge is not lost). very slowly touch the edge of the pie tin with the tip of your finger. You should feel another small spark. (The pie tin, short of electrons, attracts electrons from your finger which jump across). Drop the pie tin onto the Styrofoam tray again, and repeat. You can do this over several times before the sparks cease. Lightning is static electricity: A lightning bolt is a dramatic example of static electricity. In a thundercloud water droplets are caught in the updrafts and lifted to the top of the cloud where they freeze. Ice and hail move down in downdrafts. Ice and water bump together and electrons are transferred making positive and negative charges. The strong negative charge in the bottom of the cloud attracts positive charges in the ground, which move up the tallest objects. A “leader” of negative charge descends from the cloud seeking out a path toward the ground. When it gets close to the ground, a positive charge “streamer” reaches up to meet the negative charge. When the channels connect electricity flows and we see the lightning stroke, which may repeat until the electrical discharge is complete. The electric field often discharges between clouds. (Thunder: lightning heats the air around it to high temperatures (30,000 °C). The heated air expands explosively, creating a shockwave as the surrounding air is rapidly compressed. The air then contracts rapidly as it cools. This creates an initial crack sound, followed by rumbles as the column of air continues to vibrate.) Notes This activity is variably reliable, likely because of humidity in the air, as on humid (wet) days, objects don't hold static charges quite as well. Best inside in the winter, when the air is heated and dry. Grades taught Gr 1 Gr 2 Gr 3 Gr 4 Gr 5 Gr 6 Gr 7
