Ampere facts for kids

The ampere (pronounced "AM-peer"), often shortened to amp (Symbol: A), is the main unit for measuring electric current in the SI system. Think of electric current as the flow of tiny charged particles, like water flowing through a pipe. One amp means that a certain amount of electric charge, called one coulomb, passes a point every second.

The amp is named after a famous French scientist, André-Marie Ampère, who did important work studying electricity and magnetism. His discoveries helped us understand how electricity moves and how it can create magnetic forces.

What is an Ampere?

An ampere measures how many electric charges flow through a wire or circuit each second. It's like measuring how much water flows through a hose. If a lot of water flows quickly, that's a strong current. Similarly, if many electric charges flow quickly, that's a high ampere reading.

Understanding Electric Current

Electric current is the movement of electrons, which are tiny particles with a negative electric charge. When these electrons move in an organized way through a material, like a metal wire, they create an electric current. The ampere tells us the rate of this flow.

• A small current, like in a calculator, might be just a few thousandths of an amp (milliampere).
• A light bulb might use about 1 amp.
• A large appliance, like a microwave oven, can use 10 amps or more.

Who Was André-Marie Ampère?

André-Marie Ampère was a brilliant French physicist and mathematician. He was born in 1775 and lived until 1836. Ampère made many important discoveries about electricity and magnetism.

• In 1820, he found out that electric currents create magnetic fields. This was a huge step in understanding how electricity and magnetism are connected.
• He also developed mathematical rules to describe how these forces work. These rules are still used today in physics and engineering.
• Because of his amazing contributions, the unit of electric current was named after him.

How Amperes Are Used

Amperes are essential for understanding and designing anything that uses electricity. When you look at an electrical device, you might see its power rating in watts, but amps are also very important.

• Device Ratings: Electrical devices, like chargers or appliances, often have labels showing how many amps they need to work correctly. This helps you choose the right power supply.
• Circuit Breakers: Your home's electrical system has circuit breakers or fuses. These are safety devices that "trip" or break the circuit if too many amps flow through it. This prevents wires from overheating and causing fires. For example, a circuit breaker might be rated for 15 amps, meaning it will trip if the current goes above that.
• Battery Life: The capacity of batteries is often measured in milliampere-hours (mAh). This tells you how much current a battery can supply for a certain amount of time. A phone battery with 3000 mAh can supply 3000 milliamps for one hour, or 1000 milliamps for three hours, and so on.

Measuring Current

Electric current is measured using a device called an ammeter. You connect an ammeter in series with the part of the circuit where you want to measure the current. This means the current has to flow through the ammeter.

How the Ampere is Defined

For scientists, the ampere is defined in a very precise way. It is now linked to the elementary charge, which is the smallest possible electric charge that a single proton or electron carries. The elementary charge, written as e, is set to be exactly 1.602 176 634 × 10⁻¹⁹ coulombs. Since one amp is one coulomb per second, this definition makes the ampere very stable and accurate for scientific measurements.

Images for kids

• 

  A robot using electricity, which involves amperes.

See also

A robot using electricity, which involves amperes.

In Spanish: Amperio para niños