Question

In the CGS system, the unit of resistivity is

• A. $\Omega -cm$
• B. $\Omega -m$
• C. $C-J$
• D. $C-c{m^{-}}^1$

Answer 1

The correct option is A

$\Omega -cm$

Introduce Resistivity

We know that resistance through a circuit is directly proportional to its length.

We know that resistance through a circuit is inversely proportional to its area.

Let $R$ be the resistance, $l$ be the length, $A$ be the area, and $\rho$ be a constant, then resistance can be given as,

$R=\rho \frac{l}{A}$

where $\rho$ is the resistivity of the conductor.

Calculate the CGS unit

Upon rearranging this equation we get,

$\rho =R\frac{A}{l}$

Upon substituting the CGS units of each of these quantities in the above equation we get,

$\rho =\Omega \frac{c{m}^2}{cm}$

$=\Omega cm$

Hence, the correct answer is option (A).