Question

Which one of the following is a fundamental unit
A. Newton
B. Joule/sec
C. Watt
D. Ampere

Answer 1

Hint: The units of fundamental quantities are known as fundamental units, it is defined by the International System of Units. These units are not dependent on any other fundamental units, and all the other units such as joule, watt everything is derived from them. Some of the fundamental units are meter, kilogram, second, mol, etc.

Complete step-by-step answer:
Let us see each and every given option individually:
Option A: Newton,
We all know that Newton is the unit of force.
One newton= 1 Kg m/s(1 kg meter per second)
Its dimensional Formula is: $\text{ }\!\![\!\!\text{ }{{\text{M}}^{1}}{{\text{L}}^{1}}{{\text{T}}^{-2}}\text{ }\!\!]\!\!\text{ }$
So we can clearly see that this is a derived unit.
Now let us see,

Option B: Joule/sec
Joule/sec is a unit of power measurement.
We know that joule is the derived unit of angular momentum.
So,
1 joule = 1$kg.{{m}^{2}}.s{}^{-2}$ (1 kg meter square per second square)
The Dimensional formula for Joule/sec is:$[M{{L}^{2}}{{T}^{-1}}]$.
From this we can conclude that it is also a derived unit.
Now taking option C into consideration:

Option C: Watt
Watt is the SI unit of power, which is universally accepted.
We know that watt is a derived unit:
Its basic units are,
1 Watt= 1 $kg.{{m}^{2}}.s{}^{-3}$(1 kg meter square per second cube)
Its dimensional unit is: $[M{{L}^{2}}{{T}^{-3}}]$
So Watt is also a derived formula it is clearly seen from the above statements.
Now, taking option D into consideration.

Option D, Ampere.
Current is measured in Ampere, it is the base unit for measuring current and is accepted globally. This unit is named after Andre-Marie Ampere who was a French mathematician and physicist. Ampere is referred to as “Amp” in short.
One ampere current represents one coulomb of electrical charge.
So from the above explanation we can say that Ampere is a fundamental unit.

So, the correct answer is “Option D”.

Note: One can question that 1 ampere = 1 coulomb/sec and second is a fundamental quantity then how ampere is a fundamental unit, we have to notice that ampere is a unit of electric current and not charge passed , and in the rules for fundamental units its written that if that unit is made up of two or more fundamental unit then only it can be called a derived unit or else it's also a fundamental unit.