BrainStorms: Science with Scottlin – Opposites Attract!

Science With Scottlin

JACKSON, Miss. (WJTV) – This experiment uses soap bubbles to learn how different charges are attracted to each other. 

GRAB YOUR INGREDIENTS: a flat surface, dish soap, a cup of water, a straw, and a balloon. 

STEP 1: Once you have your flat surface, mix dish soap into the cup of water

STEP 2: Blow up a balloon

STEP 3: Coat the flat surface with soapy water and use the straw to blow a bubble onto the surface 

STEP 4: Rub the balloon against your hair to negatively charge it

STEP 5: Bring the side of the balloon that you charged near the soap bubble and watch what happens.

The bubble is attracted to the balloon and will move where ever you guide it. 

NOTE: If you get too close, the bubble will pop. 

You can even blow a smaller bubble into the bigger one, but notice the smaller one doesn’t move and isn’t affected by our charged balloon. 

Science behind this experiment: We charged the balloon by rubbing it against our hair and this is done by something called the tribo-electric effect. 

When you charge up an object, depending on the material used, it either has more positive protons than negative electrons, or more negative electrons than positive protons, like our balloon. So, we can say that our balloon is negatively charged. 

On the other hand, the soap bubble is electrically neutral, meaning that it has an equal number of positive protons and negative electrons but also contains negative and/or positive charged ions. 

When we bring a negatively charged balloon close to this bubble, the negative electrons on the balloon are attracted to the positively charged ions within the bubble. This is all because opposite charges are attracted to one another.  

Well, what about the smaller bubble that didn’t move? 

It wasn’t attracted to the balloon because the bigger bubble acts like an electrically conductive container. It’s what’s called a faraday cage, which protects objects inside from external electric effects. Kind of like if a plane is struck by lightning, the people inside of the plane aren’t affected. 

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