Question

Which of the following is not a fundamental unit?
A. cm
B. kg
C. centigrade
D. volt

Answer 1

Hint:Here in order to answer the question we will first know what does the term “fundamental unit” means and then we will see which of the given options satisfy the definition of fundamental unit.

Complete step by step answer:
The fundamental units are referred to as the foundation units in the International System of Units. These units are referred to as fundamental units since they are not derived from any other. The seven fundamental units are as follows: metre (m) is used for length, kilogramme (kg) is used for weight, second (s) is used for time, kelvin (K) is used for temperature, ampere (A) is used for electric current, candela (cd) is used for luminous strength, and mole (mol) is used for amount of material.

Since they are created by various operations on the base units, the derived units are limitless. The dimensions of derived units are expressed in terms of the dimensions of base units. A mixture of base and derived units may also be used to express derived units.The unit of electric potential difference (commonly referred to as voltage), electromotive force (commonly abbreviated to EMF), and electric potential (symbol ‘V') is the volt (symbol ‘V').

Volt is a derived unit, not a fundamental unit. The volt is a derived unit for measuring potential differences or the "energy per unit charge." “One joule of ‘energy per coulomb' of charge equals one volt.” Volt is essentially defined as $1V=kg{{m}^{2}}{{s}^{-3}}{{A}^{-1}}$in the SI system. The fundamental units – “kg, m, s, and A” – are used to derive a volt.

Hence, the correct answer is option D.

Note:The term "derived unit" refers to a unit that is derived from the basic fundamental units of the SI system, such as the meter, kilogram, second, ampere, Kelvin or centigrade, mole, and candela.