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

Verified step by step guidance

1. Identify the phenomenon: This is an example of static electricity, which occurs when there is an imbalance of electric charges within or on the surface of a material.
2. Understand the cause: When you brush your hair, electrons are transferred from one material to another. In this case, electrons are likely being transferred from your hair to the brush, leaving your hair positively charged.
3. Explain the effect: Since like charges repel each other, the individual strands of hair, now all positively charged, repel each other and fly apart.
4. Consider the conditions: Dry air is a poor conductor of electricity, which means that the charges do not dissipate quickly, allowing the static electricity to build up more easily.
5. Relate to everyday experience: This is why static electricity is more noticeable on dry days or in dry environments, as opposed to humid conditions where moisture in the air can help dissipate the charges.

Key Concepts

Static Electricity

Static electricity is the buildup of electric charge on the surface of objects. When two materials, such as hair and a brush, come into contact and are then separated, electrons can transfer from one to the other, leading to an imbalance of charges. This imbalance causes the hair strands to repel each other, resulting in the 'flying apart' effect observed on dry days.

Dry Air and Humidity

Humidity refers to the amount of water vapor present in the air. On dry days, the low humidity means there is less moisture in the air to help dissipate static charges. In contrast, humid air allows water molecules to conduct electricity, which can neutralize static charges and prevent hair from becoming charged and repelling.

Electrostatic Forces

Electrostatic forces are the attractive or repulsive forces between charged objects. When hair becomes charged through brushing, the like charges on individual strands repel each other due to these forces. This repulsion is what causes the hair to stand apart, illustrating the principles of electrostatics in action.