Electrical Corn Starch (Andrew Salg)

Author

Andrew Salg

HS PS1-3 Plan and conduct an investigation to gather evidence to compare the structure of substances at the bulk scale to infer the strength of electrical forces between particles.
HS PS2-6 Communicate scientific and technical information about why the molecular-level structure is important in the functioning of designed materials.

Materials Needed:

1/2 a cup of cornstarch

1/2 a cup of vegetable oil

A bowl or measuring cup

1 Balloon

A large spoon

Something to conduct static electricity (e.g. hair, clothing, pieces of wool)

Prior knowledge & experience:

The students should already know electrons as a type of molecule found in

elements and compounds. The students should also already know that

balloons can cause static electricity. The students must also have the

knowledge to be able to observe closely to notice the interaction between the

balloon and the corn starch.

Root question:

What will happen to the corn starch when the balloon is brought close the

corn starch in the spoon?

Target response:

The corn starch will jump up in the air trying to touch the balloon. This is

because of static electricity built up in the balloon, and the neutral particles in

corn starch will be drawn to the negative charge of the balloon. The reason is

because corn starch is a non-Newtonian fluid because it does not know

whether to act as a solid or a liquid, so it will not act like a traditional

liquid according to Newton's laws of liquids. The balloon and the spoon with

the corn starch must be close or else it will not work. This can not be done

with a larger amount of corn starch because the neutral charge will be too

great to overcome. However, if a larger object with a charge came by, it may

be possible, but it will not be that discrepant.

Common Misconceptions:

The fluid will do nothing is the most common misconception that students

have. Others think that their will be a spark in some cases because of the

static electricity.

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