Aluminium Can Static Roll

Statically charged balloons and the cans that are attracted to them... Learn how you can create static electricity by rubbing a balloon against the hair on your head. See how opposite charges attract by rolling an aluminium can across a table using the balloon, but without touching the can!

Australian Curriculum links

  • Science > Physical Sciences > Year 2 > ACSSU033
  • Science > Physical Sciences > Year 4 > ACSSU076

You'll need

  • head of hair (preferably attached to a body) or a jumper
  • inflated rubber balloon
  • empty, clean and dry aluminium can

Try this

  1. Rub the balloon on your hair or a jumper to give it a static charge. Dry, clean hair works best and sometimes you might need to try a few people’s hair before you can build up enough of a charge.
  2. If the balloon is charged, hair will stick to it as you move the balloon away from your head.
  3. Lay the aluminium can on its side on a flat table where it has room to roll.
  4. Hold the charged balloon very close to the aluminium can (but not touching the can or the table) then slowly move the balloon away from the can. (The can will start to roll and follow the balloon!)

What's happening?

Have you ever felt a painful “ZAP” while jumping on a trampoline or getting out of a car but weren’t quite sure who you should blame? Ever walked past a television and all the hairs on your arms have stood on their ends but it wasn’t even cold? Have you ever sat awake at night and could swear there was something sitting in your cupboard staring at you? Well live in fear no longer, as chances are you were merely the innocent victim of static electricity—except for the monster in your cupboard.

Static electricity is again the culprit with our balloon and can. When you rub the balloon on your hair you’re moving around tiny little pieces of electricity called electric charges. There are two kinds of electric charges, positive charges and negative charges. By rubbing the balloon on your hair you’re taking negative charges from the hair and transferring them to the balloon. The balloon ends up negatively charged and the hair becomes positively charged. Positive and negative charges are attracted to each other so the hair tries to stick to the balloon. It’s the same with the can. The can has both positive and negative charges and its positive charges are very attracted to the negative charges on the balloon, which causes the can to roll towards the balloon.

The ultimate source of static electricity comes from the interesting properties of atoms—the tiny pieces of matter that make up all of the materials in our universe, such as water, tables, rocks and even us. Atoms are often visualised as miniature solar systems with a positively charged nucleus (where the sun would be), made up of neutrons and protons, being orbited by negatively charged electrons arranged in ‘shells’. Under normal circumstances atoms are neutral. They have no charge because the positive charge of the nucleus is balanced out by the negative charge of the orbiting electrons.
However, electrons aren’t necessarily stuck forever to any particular atom. To a certain extent they can move around and it’s this movement which creates the static charge. When objects come in contact they can sometimes exchange electrons. This is called (warning: scientific jargon alert!) contact induced charge separation and results in one material (the material that loses electrons) becoming positively charged and the other material (the material that gains electrons) becoming negatively charged.

Real world links

Lightning bolts are caused by a build-up of static charge in clouds. Benjamin Franklin supposedly showed that clouds contain electrical charge through his famous kite experiment, first proposed in 1750. While there is dispute about the circumstances of this experiment, it is unlikely that Franklin flew his kite in an actual lightning storm as a lightning strike to his kite would have probably killed him. Professor Georg Wilhelm Richmann of Germany showed this to be the case when in 1753 he was electrocuted after hearing thunder and deciding to see what would happen if he stuck a metal rod into the air.