Basic SI units

Which of the following is NOT a basic SI unit?

a) Candela

b) Kelvin

c) Mole

d) Newton

e) Ampere

Answer: d

Explanation

The basic SI units (Système Internationale d’Unités) are the metre, kilogram, second,

kelvin, candela, mole and ampere. The candidate must know these and their definitions.

All other units are derived and may be expressed in terms of these seven basic

units. It is an interesting paper exercise to consolidate understanding of the subject by

choosing any derived unit then by application of the laws of physics and conversion

factors, prove that the unit may be expressed in terms of these basic seven units. For

example, prove that 1mmHg = 133.3 kg/m/s2 or that 1 ohm = 1 kg.m2/s3/amp2.