RAS question
The SI unit of electric current is:
Correct answer: (C) Ampere.
The SI base unit of electric current is the ampere, with the unit symbol A.
Explanation
The ampere is the right choice because electric current is one of the SI base quantities, and BIPM's SI base units table lists electric current with the quantity symbol I, the unit name ampere and the unit symbol A. A standard school-level way to remember the unit is that one ampere corresponds to the flow of one coulomb of charge per second. That is why the question is asking for ampere, not a derived electrical unit used for voltage, power or resistance. The name honours French physicist Andre-Marie Ampere, but for exam purposes the key link is direct: electric current maps to ampere in the SI base-unit system.
Why the other options are wrong
- (A) Volt is the SI unit of electric potential difference, so it measures voltage rather than electric current.
- (B) Watt is the SI unit of power, so it describes the rate of energy transfer rather than current.
- (D) Ohm is the SI unit of electrical resistance, so it belongs to opposition to current flow rather than current itself.
Concept
This tests the basic SI-units portion of Science and Technology, especially the distinction between base units and common derived electrical units. It recurs in RAS because unit identification is a quick way to test conceptual clarity in physics without lengthy calculation.