To correctly define a volt, we need to understand the basic concept of what a volt represents in terms of electrical potential difference.
A volt is the unit of electric potential difference or electromotive force in the International System of Units (SI). It is defined in terms of energy per unit charge. Specifically, one volt is the potential difference between two points in a conductor when one joule of energy is used to move one coulomb of charge between those two points.
Let’s break down each option given in the question:
(a) A volt is a joule per ampere.
(b) A volt is a joule per coulomb.
Now, let's analyze each statement:
- Statement (a): A joule per ampere would be related to another physical quantity. In fact, if we consider the units, a joule per ampere does not define volt. This is not the correct definition according to the SI unit system.
- Statement (b): A volt is a joule per coulomb. This correctly describes the relationship where one volt equals one joule of work done to move one coulomb of charge. This is indeed the proper definition of a volt.
Therefore, after analyzing both statements, the correct definition of a volt is:
(b) A volt is a joule per coulomb.
Hence, the correct answer to the question is (b) a volt is a joule per coulomb.
