Separating Salt & Pepper with Balloons

Contributed by Shubhang Tyagi

Introduction 

Do you want to be able to control minuscule particles like salt and pepper? Do you have hair? If you answered yes to both of these questions, you are in luck. A physics phenomenon in electrostatics allows us to use out hair to control salt and pepper! 

Materials 

• Balloon
• Salt
• Pepper
• A full head of hair
• Colored notebook

Procedure 

● Place the colored notebook on a flat surface. 

● Pour out a mixture of salt and pepper with an arbitrary amount of each condiment onto the center of the notebook. 

● Blow up the balloon. 

● Aggressively rub the balloon for 1 minute on your head. 

● Place the balloon over the mixture of salt and pepper and observe what happens. 

● Some particles from the mixture should rise up and stick to the balloon, whereas others will glide away from the balloon. 

Physics Concepts and Questions 

The separation of the salt and pepper particles happens due to the fact that unlike charges attract and like charges repel. When the balloon is rubbed aggressively on your head, lost electrons from your hair attach themselves to the balloon. This makes the balloon have an excess negative charge, since electrons are negatively charged. The mixture of salt and pepper has some particles that are positively charged and some that are negatively charged. The particles that are positively charged will rise up and stick to the balloon due to the attraction of unlike charges. Similarly, the particles that are negatively charged will glide away from the balloon due to the repulsion of like charges. 

Conclusions and Further Investigations 

Since we are now aware of the science behind like and unlike charges, try to see what other household items can be moved with just a balloon. Rubbing a comb on woolen clothes has the same effect, so try charging up a comb and holding it near a stream of water.