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Physics · 术语表

什么是 Voltage？

又称： volt

Definition 56.1 Primary & Middle School Physics · 第 56 章 — Voltage and the Voltmeter

The voltage $U$ between two points of a circuit measures the electrical push available between them — how hard the current is driven from one point to the other, as a waterfall’s height measures how hard it drives the millwheel. Voltage is always a between: between the two terminals of a battery, between the two sides of a lamp — never at a single point alone. Its unit is the volt ( $\mathrm{V}$ ), honoring the inventor of the first battery.

示例

Example 56.2 (The volt family album)

A single round cell: $1.5\,\mathrm{V}$ . The flat pocket battery: $4.5\,\mathrm{V}$ — three cells nose-to-tail inside one wrapper. The rectangular nine-volt with both terminals on top: $9\,\mathrm{V}$ , six hidden cells. A car battery: $12\,\mathrm{V}$ . The wall socket: $230\,\mathrm{V}$ — more than a hundred and fifty little cells’ worth of push, which is the whole quantitative content of “the socket, never”. Lightning between cloud and ground: hundreds of millions of volts, briefly.

Example 56.10 (The open switch’s confession)

Lamp dark, switch open — where did the push go? Measure: across the dark lamp, $0\,\mathrm{V}$ ; across the open switch, the full $4.5\,\mathrm{V}$ . The battery’s push stands entire across the gap, waiting — the one place in the loop where two points are truly “far apart” electrically. Close the switch and the readings trade places. An open switch is where the voltage waits.

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