Benita Sen
There’s nothing like an interesting experiment to get your child hooked to science.
Try this experiment with your child, and witness the intriguing effect together. If she is old enough, add explanations about electrons and protons. If not, just enjoy the experiment.
Things you need
- Plastic comb
- Thread
- Woollen sweater
- A few pieces of puffed rice
- Cellotape
The Experiment
- Tie a 12-inch long thread to a grain of puffed rice.
- Glue the thread to the edge of a table where it can swing freely.
- Vigorously rub the comb on a woollen sweater.
- Slowly, bring the comb close to the rice grain without touching it.
- The rice grain will swing towards the comb and stick to it.
- Let it remain there. It will soon fall away.
- Then move the comb close to the rice grain. It will move away from the comb this time.
The Explanation
Static electricity is what made the puffed rice grain and comb interact this way. You experience static electricity when your hair sticks to your comb, or your synthetic clothes crackle in dry weather.
Atoms in an object are made of electrons, neutrons and protons. Each one has an electric charge.
- Electrons — negative
- Protons — positive
- Neutrons — no charge
When electrons move from one atom to another, the charge of an atom changes. Atoms usually transfer electrons so that they can maintain the balance of having the same number of electrons and protons in each atom. Materials with the opposite electrical charge attract each other. Those with the same charge repel each other.
When you rubbed the comb on the sweater, electrons moved between the two.
Rubbing the comb on the sweater made electrons move into the comb, giving it a negative charge. So the puffed rice grain was attracted to it and electrons moved from the comb to the grain. After that, the comb and the rice grain had the same electrical charge, so they repelled each other.
Encourage your child to try such experiments. Conducting experiments together is definitely more inspiring than just buying her a book of experiments, or showing her a science-based website. You’ll rediscover the joy of science too!
Also read: Science at home: Lemon volcano