# Floating Octopus

Get charged up and feel elevated in this amazing static electricity activity. Watch as negative charges repel to suspend an octopus in mid–air!

• Science > Physical Sciences > Year 4 > ACSSU076
• Science > Physical Sciences > Year 6 > ACSSU097

## You'll need

• Scissors
• Plastic shopping bag
• Modelling balloon (type used for balloon animals)
• Balloon pump
• Piece of cloth (silk or wool works best) or a head of hair
• 2 helpers

## Try this

1. Make your octopus: Using the scissors, cut a 2 cm wide and 30 cm long strip from the plastic bag. Fold the strip in half and cut up along the strip to the fold to make eight ‘legs’, leaving at least 1 cm of the strip near the fold.
2. Cut the modelling balloon in half, tie off the half with the open end, use the balloon pump to blow up each half and then tie them off.
3. Charge up the balloons by rubbing them with the cloth or on your hair. You will know the balloons are fully charged when they attract your hair.
4. Charge up the octopus by placing it on a table and carefully rubbing it with the cloth.
5. Give a balloon to each of your helpers and explain that their task is to keep the octopus in the air using the balloons and that they should be able to do this without actually touching the octopus.
6. Throw the octopus into the air between your helpers and watch them use the balloons to keep the octopus aloft.

## Further investigation

Have a competition to see which team can keep their octopus floating the longest. Try charging the octopus and balloons with different materials (silk, wool, hair, cotton, polyester, etc.) to determine which material builds the best charge.

## What's happening?

This activity works using static electricity. When you rub the balloon on your hair (or the fabric), you’re moving around tiny little pieces of electricity called electric charges. There are two kinds of electric charges, positive and negative. Positive and negative charges are opposite charges and are attracted to each other. Two charges that are the same will repel or push away from each other.

Rubbing the balloon on your hair (or the fabric) causes negative charges to move from your hair (or the fabric) to the balloon. The balloon becomes negatively charged. Your hair loses negative charges and becomes positively charged. Your positively charged hair clings to the negatively charged balloon because opposite charges are attracted to each other. Rubbing the fabric against the octopus causes the octopus to become negatively charged. The negatively charged balloons and the negatively charged octopus pushed away from each other because similar charges repel. Your skin has both positive and negative charges. If the octopus gets too close to your skin, the positive charges on your skin will be attracted to the negative charges in the octopus, resulting in the octopus clinging to you!

The effects of static electricity arise from the interesting properties of atoms. Atoms are the tiny pieces of matter that make up all of the materials in our universe, such as water, tables, rocks and even our bodies. An atom is often imagined as being like a miniature solar system, with a positively charged nucleus (where the sun would be) made up of neutrons and protons, being orbited by negatively charged electrons.

Under normal circumstances, an atom is neutral because it has equal amounts of positive and negative charge. The positive charge of the nucleus is balanced by the negative charge of the orbiting electrons, so the atom has no overall charge. However, electrons aren’t necessarily stuck forever to any particular atom. When objects come into contact with each other they can sometimes exchange electrons. This is called ‘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. Static electricity is the result of this separation of positive and negative charge.