十万个为什么·科学启蒙30篇（4）

6 / 30

为什么气球摩擦后能吸小纸片

Rubbing a balloon on hair transfers electrons from hair to rubber, giving the balloon a negative static charge.
Neutral paper bits have positive and negative charges evenly spread—but they become polarized near the charged balloon.
The balloon’s negative charge repels electrons in the paper, leaving the near side slightly positive and attractive.
This electrostatic force is strong enough to lift lightweight objects against gravity for a few seconds.
Dry air helps because moisture would let charges leak away quickly through thin water films.
The effect fades as charges slowly equalize or leak into the air, especially in humid conditions.
Unlike magnets, static attraction works on insulators like paper, plastic, or hair—not just metals.
You can test polarity by seeing whether two charged balloons push apart—confirming like charges repel.