The SI unit for measuring an electric current is theampere, which is the flow of electric charge across a surface at the rate of one coulomb per second. Electric current is measured using a device called an ammeter.

The SI unit for measuring an electric current is the ampere, which is the flow of electric charge across a surface at the rate of one coulomb per second. Electric current is measured using a device called an ammeter.

The correct answer is option 'A', Ampere. The SI unit of electric current is Ampere, which is named after the French physicist André-Marie Ampère.

Electric current is defined as the flow of electric charge through a conductor. It is the rate at which electric charges pass through a given point in a circuit. The flow of electric charges is usually caused by the motion of electrons in a conductor.

Here is a detailed explanation of the SI unit of electric current:

- Definition of Ampere:
Ampere is defined as one coulomb of electric charge passing through a point in a circuit per second. It is represented by the symbol 'A'. One Ampere is equivalent to one coulomb per second.

- Coulomb:
Coulomb is the unit of electric charge. It is named after the French physicist Charles-Augustin de Coulomb. One coulomb is equal to the charge of approximately 6.242 × 10^18 electrons.

- Importance of Ampere:
Ampere is a fundamental unit in the International System of Units (SI) and is used to measure electric current. It is essential in various fields of physics and engineering, including electronics, electrical circuits, and electromagnetism.

- Practical Measurement of Current:
The current in a circuit can be measured using a device called an ammeter. An ammeter is connected in series with the circuit to measure the flow of current. The reading on the ammeter is in Amperes (A).

- Historical Background:
The unit Ampere is named after André-Marie Ampère, a French physicist and mathematician who made significant contributions to the field of electromagnetism. Ampère conducted experiments and formulated mathematical equations to describe the relationship between electric current and magnetic fields.

In conclusion, the SI unit of electric current is Ampere (A). It is defined as the flow of one coulomb of electric charge per second. Ampere is a fundamental unit used to measure current in various fields and is named after the French physicist André-Marie Ampère.