十万个为什么·科学启蒙30篇（4）
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Why Rubbed Balloons Attract Paper Bits
为什么气球摩擦后能吸小纸片
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Rubbing a balloon on hair transfers electrons from hair to rubber, giving the balloon a negative static charge.
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Neutral paper bits have positive and negative charges evenly spread—but they become polarized near the charged balloon.
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The balloon’s negative charge repels electrons in the paper, leaving the near side slightly positive and attractive.
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This electrostatic force is strong enough to lift lightweight objects against gravity for a few seconds.
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Dry air helps because moisture would let charges leak away quickly through thin water films.
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The effect fades as charges slowly equalize or leak into the air, especially in humid conditions.
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Unlike magnets, static attraction works on insulators like paper, plastic, or hair—not just metals.
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You can test polarity by seeing whether two charged balloons push apart—confirming like charges repel.