Question

Find the dipole moment if dipole consists of two opposite charges each of magnitude $1.6 \times {10^{ - 19}}$ Coulomb at separation 1 Angstrom.
A) $1.6 \times {10^{ - 19}}C - m$
B) $1.6 \times {10^{ - 29}}C - m$
C) $3.2 \times {10^{ - 29}}C - m$
D) $3.2 \times {10^{ - 19}}C - m$

Answer 1

Hint: The electric dipole moment is calculated by using formula-
$P = qD$
where $q$ is the magnitude of the charge
$P$ is the dipole moment
$D$ is the separation between two charges
By putting the values in their respective places, we can easily get the value for the dipole moment.

Complete step by step answer:
When two equal and opposite charges $ + q$ and $ - q$ respectively are separated by a fixed distance then this combination is called Electric Dipole. The midpoint of both the charges $ + q$ and $ - q$ respectively is called the center of the dipole.
The product of the magnitude of the charge on the dipole and separation between two charges is called the electric dipole moment. The electric dipole moment is a vector quantity and is denoted by vector $\overrightarrow P.$
The direction of the dipole moment is from a negative charge to a positive charge. This sign convention is only followed in Physics. In Chemistry, this sign convention is taken opposite, that is, from positive charge to negative charge. The line with the direction of the electric dipole is called the axis of dipole.
Now, to find the dipole moment having magnitude of charge $1.6 \times {10^{ - 19}}$ and at separation $1$ angstrom
According to question, it is given that
$q = 1.6 \times {10^{ - 19}}$
$D = 1\dot A = {10^{ - 10}}m$
Therefore, putting these values in the formula-
$
P = qD \\
\Rightarrow P = 1.6 \times {10^{ - 19}} \times {10^{ - 10}}C - m \\
\Rightarrow P = 1.6 \times {10^{ - 29}}C - m \\
 $

Therefore, the electric dipole moment is $1.6 \times {10^{ - 29}}C - m$. Hence, the correct answer is option (B).

Note:
Electric dipoles are also prominent in chemistry. In many molecules, the center of positive and negative charges coincide at some point due to which distance between two charges is zero. The examples of such molecules are carbon dioxide and methane. This is called non-polar molecules. Polar molecules are just the opposite of non-polar molecules.