On a dry day, your hair flies apart when you brush it. How would you explain this?

Name: Problem 25, Chapter 4: Basic Chemistry
Uploaded: 2020-06-07T15:59:40-08:00
Duration: 2 min 47 s
Channel: Jason Boomer
Description: On a dry day, your hair flies apart when you brush it. How would you explain this?

On a dry day, your hair flies apart when you brush it. How...

Key Concepts

Electrostatic Repulsion

Electrostatic repulsion is the force that drives similarly charged objects to push away from each other. In the context of hair, once the strands acquire the same electrical charge from brushing, they repel one another, causing the hair to fly apart due to the force described by this principle.

Triboelectric Effect

The triboelectric effect is the phenomenon where certain materials become electrically charged after they come into frictional contact with a different material. This effect explains why brushing hair can transfer electrons, resulting in charged hair strands that repel each other under low humidity conditions.

Static Electricity

Static electricity is the build-up of electrical charges on the surface of objects, which can occur when electrons are transferred from one material to another. This build-up leads to an imbalance of charges that remains until the charges can recombine or dissipate, often observed when materials are rubbed together.

Friction

Friction is the resistance to motion when two surfaces come into contact. In everyday situations, such as brushing hair, friction between the brush and the hair causes electrons to be displaced, leading to the build-up of static electric charge on the hair.

Transcript

00:04 So this question is asking about hair that kind of repels each other when you brush it when it's a really dry day out.

00:17 And so the question is, what is causing that to happen? and so what's actually happening, so if we think about our hair, our hair, of course, is composed of atoms.

00:30 And as we brush it, we have this friction force.

00:33 And sometimes what happens with that friction force is, that the electrons will actually, since they're on the outside of the atom and they're so small, it's really easy to move them, they can get ripped away from the atom that they're supposed to be on.

00:48 So maybe the electrons are being moved away from the brush toward the hair, or maybe they're being moved away from the hair toward the brush.

00:58 But whatever it may be, let's say that the brush is giving electrons to the hair.

01:03 So now all of these hair, all these atoms in the hair, are negatively charged.

01:11 They have a slight negative charge to them because they've gained some extra electrons.

01:16 And what do we know about negative charges? negative charges are going to repel each other.

01:21 So we end up with this static electricity because they've gained these negative charges and negatives repel other negatives.

01:31 And so then your hair does this thing where it spreads out.

01:36 And why does this only happen on dry days? i guess is the next...

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