Science

Static Electricity Soda Can

by Amy Collins July 18, 2018

You will need:

• 1 Gratnells shallow (F1) tray
• 1 clean, empty, fizzy drinks can
• 1 inflated balloon
• Optional: bigger trays (Gratnells A3 or Art trays), additional cans, more balloons, a stopwatch.

What to do:

1. Place the can on its side in the centre of the shallow tray.
2. Rub the balloon quickly back and forth against your clothing for at least 30 seconds to ‘charge’ it – a nice woolly jumper would work well.
3. Predict what will happen when you move the charged balloon close to the can.
4. Move the charged balloon close to the can, but not touching it, and observe what happens.

What is happening?

It’s all about electrons. Electrons can move from atom to atom and object to object. When the balloon is rubbed against the jumper, an excess of invisible electrons (negatively charged) build up on the surface of the balloon. This is called static electricity. The electrons have sufficient power to pull very light (positively charged) objects towards them, like the can. Static electricity dissipates over time, so the charge won’t last very long, but you can build it back up again by recharging the balloon on your jumper.

Other things to try…

• Soda Can Races! Working with some friends or classmates, place several cans lined up along the edge of a Gratnells Art or A3 tray, each charge up your own balloon and see which can makes it to the opposite side of the tray first powered only by static electricity.
• Use a stopwatch to time how long it takes for the can to travel the full length of the tray.
• Experiment with what surface you use to ‘charge’ your balloon (e.g. the hair on your head, a shirt made of man-made fibres, a cotton t-shirt, jumpers made of different wools etc)
• Experiment with how long/how many strokes you charge it for, do these variables effect the speed of travel?
• Does the size of the balloon effect the speed of travel?
• Does it work on a ping-pong ball or other non-metal objects? Try it with some small (0.5cm square) torn up pieces of tissue. The trays are great at stopping your chosen objects from escaping!
• How much water (or other weights) can you put in the can before the balloon is unable to move it?

Tip: static electricity experiments work much better on a dry, non-humid, day.

Health & Safety

As with all Gratnells Learning Rooms What’s In My Tray Activities you should carry out your own risk assessment prior to undertaking any of the activities or demonstrations.