Definition of 1 Ampere

Learn about the definition of 1 Ampere, the unit of electric current in the International System of Units. Explore real-world examples and case studies to understand its significance.

What is an Ampere?

An ampere, often abbreviated as ‘amp,’ is the unit of electric current in the International System of Units (SI). It is named after the French mathematician and physicist André-Marie Ampère, who made significant contributions to the field of electromagnetism.

How is 1 Ampere Defined?

The ampere is defined as the constant current that, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed one meter apart in a vacuum, would produce a force between the two conductors equal to 2 x 10^-7 newtons per meter of length.

Real-world Examples

1. Charging your phone: When you plug your phone into a charger, the current flowing through the charging cable is measured in amperes.

2. Light bulbs: The current flowing through a light bulb determines its brightness. For instance, a typical 60-watt incandescent light bulb draws about 0.5 amperes of current.

Case Studies

Case Study 1: Electric Vehicles (EVs)

  • EVs are powered by large batteries that require high currents to charge quickly.
  • Tesla Model S, for instance, can draw up to 11.5 amperes while charging at a standard 120-volt outlet.

Case Study 2: Circuit Overloading

  • If too many appliances are plugged into a single circuit, it can draw more current than it is designed to handle, leading to overheating and potential fire hazards.
  • To prevent this, circuit breakers are designed to trip when the current exceeds a certain threshold, typically measured in amperes.


The ampere is a fundamental unit of electrical measurement that plays a crucial role in various everyday applications, from charging electronic devices to powering electric vehicles. Understanding the definition of 1 ampere is essential for safely working with electricity and ensuring the efficient operation of electrical systems.

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