DIY Science: It’s Electric! (Cornstarch)

 

Today at the Greensboro Science Center we are working on a science experiment that is borderline magic. We are going to create and witness the power of a static charge!

For this experiment you will need:

  • 1/4 cup of cornstarch
  • 1/4 cup of vegetable oil
  • One balloon ( we used a standard-sized one, size shouldn’t really matter)
  • A mixing bowl
  • A large spoon
  • Measuring cup
  • Adult supervision

Begin your experiment by gathering the necessary materials.

balloon_1

Next, add your cornstarch and vegetable oil into your bowl. 

Stir your mixture with your spoon until it is free of any lumps. You will want to achieve a fairly runny consistency in order to get the desired results from this experiment. 

Next, blow up your balloon and tie it.

It is now time to statically charge your balloon. This can be done by  rubbing the balloon against your hair, shirt, or a rug using  a back and forth motion for a few seconds (for best results and a little humor, we suggest using your hair). 

balloon_9

Helpful tips:

  • The experiment will not work if your balloon makes contact with another object, as this causes the balloon to lose its static charge.
  • ay attention to which part of the balloon you rubbed. The part that made contact with your hair or other charging surface is the only area of the balloon that will have enough static charge to noticeably affect the cornstarch mixture.

Now it’s time to observe something really cool! Take your balloon and hold it just above your mixing bowl, scoop some of the mixture onto your spoon.  Holding the spoon close to the charged side of the balloon slowly begin to drip the mixture down into the bowl.  Once you see the cornstarch mixture jump towards the balloon, try moving the spoon mixture away. You should notice that the cornstarch mixture is no longer “jumping” towards the balloon.

 

Scientific Explanation:

When you rub the balloon on a coarse surface (like your hair), you transfer electrons from the rubbed surface to the balloon,  giving the balloon additional electrons. These new electrons generate a negative static charge which are attracted to the cornstarch which has a neutral charge.

When an object has a negative charge, it will reject the electrons of other objects, and attract that object’s protons. When the neutrally charged object is light enough, like our dripping cornstarch, the negatively charged object will attract the lightweight object. One thing you might notice is that the cornstarch won’t be attracted to the balloon while it is in the bowl. This is because there are stronger forces acting on the cornstarch (like gravity) for the cornstarch mixture to jump up out of the bowl. By dripping the cornstarch, you are creating a thinner string of  corn starch molecules which will be light enough to be pulled by the static force of the charged balloon allowing it to  move and “jump” towards the balloon with ease.  

 

 

 

 

 

 

 

 

 

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This entry was posted in DIY Science, Science Explained by greensborosciencecenter. Bookmark the permalink.

About greensborosciencecenter

The Greensboro Science Center offers three fascinating attractions in one wild destination! We are the only facility in North Carolina that offers an aquarium, museum, and zoo. Spend the day with us and come nose to beak with playful penguins, get eye to eye with awesome otters, explore the human body, experience Mother Nature’s fury and fun, and encounter exotic animals like tigers, meerkats, and lemurs!

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