A volt measures electrical push, while an amp measures how much charge flows.

The longer version

Voltage describes the push behind each unit of charge, while current measures how much charge passes a point each second. A useful comparison is water in a pipe: pressure corresponds to voltage and flow rate corresponds to current. Both are needed for energy to be delivered.

Power is the product of the two, so a small push with a large flow can do as much work as a large push with a small flow. Resistance links them, since a given push drives less flow through a narrower path. Both quantities are normally measured with instruments designed for that purpose.

Where this entry sits

Everyday physics and chemistry hide small wonders in plain sight, from kitchen reactions to the light in the sky. These short facts explain matter, energy, electricity, magnets, sound, and the simple units we use to measure the world. The full list sits on the Science and Physics page, where every entry is listed in order.

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More From Science and Physics

Eight more entries

The meter was originally defined as one ten-millionth of the distance from equator to pole.

A kilogram was once defined by a physical cylinder kept in a vault in France.

Celsius sets freezing at zero and boiling at one hundred for pure water at sea level.

Absolute zero is the coldest possible temperature, where particles nearly stop moving altogether.

An atom is mostly empty space, with tiny electrons orbiting a dense central nucleus.

Molecules in a gas move freely, while those in a solid only vibrate in place.

Density compares mass to volume, which explains why a small rock can feel heavy.

Dropped objects fall at the same rate regardless of weight when air resistance is removed.

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