Just like the Ghost from the local haunted house, these balls become invisible when placed in water, hence the name ‘Ghost Brains’. They are amazing to see and teach the concepts of water absorbing polymers, transparent, translucent and refraction.
Remember
1. These are chemicals and expand in water SO keep out of reach of children and pets. They are NOT food and should not be eaten.
2. If swallowed, contact medical help immediately.
- Place the ghost brains in the water and leave over night.
- Place your hand in and collect the invisible brains, which have absorbed water and become invisible.
- Place the container first with no water, in front of an object. The light from the object is scattered and the image is hard to read. This is called translucent.
- When filled with water, the light from the object passes through the water & balls with minimal bending (refraction) and the image is clear. This is called transparent.
Check out the ‘Wacky Science’ video of this experiment and ‘What’s Going On’ series link. They are currently ‘In Production’, so check back soon…..
These fantastic little Ghost Balls do their magic due to a physics phenomenon called ‘refraction’.
Refraction just means bending of light. We see objects due to how light enters our eyes and the beads seem invisible to use at first because the light from the back of the card passes through them and into our eyes in nearly a straight line. The light passes through the beads without bending very much at all and so we see the card and ‘think’ there is nothing in front of them.
The image below shows the container with NO water. That means air is between the ghost brains and causes the light to bend (refract). The bending light means when the beams of light enter our eyes, its direction has been changed and we see the balls.
When we placed water in the container, the air spaces were filled in with water. Since the beads contain mostly water as well, the density between the two is very similar (called refractive index). This means the light from the card does NOT bend that much and its direction remains mostly straight. We see this as the beads disappearing.
If you would like
– more details,
– pictures of the second half of the experiment
– information on how to investigate this further
– links to everyday examples
– management hints & teaching pointers (5P Teacher develpoment program)
 ….. then why not subscribe to one of the following
(1) Crazy science Club
(2) 5P Teacher Training course called ‘Looney Lab  Classroom Creations‘
Or you can purchase the ‘Bright Sparkes Guide’ of this demonstration only ($2.50) which has:
- HD pictures of experiment steps
- Detailed explanation of science
- Mini-challenge section (another experiment)
- Making it a ‘Scientific Method’ experience
- Graphing opportunities
- REAL links and descriptions to everyday examples of concept.