Why does hair stand up in static?
Show answer & explanation
Answer: Like charges repel each other
Like charges repel each other ✓ — Correct! Rubbing (balloon on hair, dry hair combing) transfers electrons through triboelectric effect. Hair strands gain same charge (all positive or all negative). Like charges repel through electrostatic force—strands push away from each other. Each hair tries to maximize distance from others—stand up and spread out! More charge = stronger repulsion = spikier hair. Van de Graaff generator demonstration: person touching it gets extremely charged—hair stands straight up! Humidity reduces effect (moisture conducts charge away).
Air pressure changes — Wrong. Air pressure doesn't change. Static electricity—like charges on hair strands create repulsive forces pushing strands apart.
Muscles contract involuntarily — Wrong. No muscles in hair. Hair stands because each strand has same electric charge—electrostatic repulsion pushes them apart.
More Physics in Daily Life questions
- In a warm office that already reads 26 C, which change can make people feel cooler without lowering the thermostat?
- Why might 26 C feel acceptable in a breezy naturally ventilated summer building but too warm in a sealed winter office?
- On a warm humid day, why can the same 27 C room feel much worse once you start sweating?
- Why can moving air make a 27 C room feel cooler without changing the thermometer?
- Which hidden factor can make a desk beside a cold window feel chilly even when the thermostat across the room still reads 22 C?
- In the same 22 C room, why might someone who just climbed stairs feel warm while someone sitting in a T-shirt feels chilly?