Ampere (A)
The ampere, often shortened to "amp," is the unit of electric current in the International System of Units (SI). It measures the amount of electric charge passing a point in an electric circuit per unit time.

One ampere is defined as the current that flows with electric charge of one coulomb per second.
Practical Definition:

If a wire carries one coulomb of charge (approximately \(6.242 \times 10^{18}\) electrons) past any point in the wire in one second, the current in the wire is one ampere.

Symbols and Notations

Symbol for Ampere:

The symbol for ampere is [A].

SI Base Units:

The ampere is one of the seven base units in the International System of Units (SI).

Common Symbols and Units Related to Electric Current:

-Current (I):

The symbol "I" is often used to denote electric current in formulas and equations.

-Microampere (μA):

One millionth of an ampere (\(1 \mu A = 10^{-6}\) A).

-Milliampere (mA):

One thousandth of an ampere (\(1 mA = 10^{-3}\) A).

- Kiloampere (kA):

One thousand amperes (\(1 kA = 10^3\) A).

Example Uses:

Household Appliances. Household electrical devices typically operate at currents ranging from a few milliamperes (mA) to tens of amperes (A).

Industrial Equipment:

Industrial machines and equipment may use currents in the range of hundreds to thousands of amperes (A).

Relationship to Other Electrical Units:

Voltage (V):

Defined as the electrical potential difference between two points. The relationship between current (I), voltage (V), and resistance (R) is given by Ohm's Law: \(V = IR\).

-Resistance (R):

Measured in ohms (Ω), it quantifies how much a material opposes the flow of electric current.

Power (P):

Measured in watts (W), power in an electrical circuit is given by the product of current and voltage: \(P = IV\).