Question

Debye is the unit of:
A). Electric flux
B). Electric dipole moment
C). Electric potential
D). Electric field intensity

Answer 1

Hint: Debye is a unit that was given in honor of Peter J.W Debye. It is not an SI unit. Debye units are used in molecular chemistry and physics as they are more convenient than some SI units for measuring small quantities related to atoms and molecules.

Complete step by step answer:
As explained in the hint, the Debye $\left( D \right)$ is a unit for electric dipole moment. However, it is not the SI unit of electric dipole moment. The SI unit for electric dipole moment is Coulomb-metre $\left( C.m \right)$.
The Debye unit was formulated since it is very inconvenient to measure the electric dipole moments of atoms and molecules in molecular physics and chemistry using the SI units which are very large for this purpose.
For example, the dipole moments of some typical diatomic molecules range from $0D$ to $11D$.
In terms of the SI units, the Debye can be written mathematically as
$1D\approx 3.33\times {{10}^{-30}}C.m$
Hence, we can see that the Debye is much smaller than the SI units and is in fact, much more convenient for measuring the electric dipole moments of atoms and molecules.

Note: Students should know about some important non SI units and units from other systems of units such as the CGS and FPS system. Sometimes questions are set purposefully in these units but the answer required in SI units to check whether the student can identify and convert the unit properly or not. Hence, it is best that students keep in mind some important non SI units such as Debye, dyne, etc.