Question

Which one of the following is the definition of specific resistance ?

• A. It is resistance of a wire of length $1cm$ and volume $2c.c.$
• B. It is the resistance of a wire of volume $1c.c.$ and mass $1gm$
• C. It is the resistance of a wire $1cm$ length and $1sq.cm$ cross section
• D. It is the resistance of a wire of volume $1c.c.$ and potential difference $1volt$

Answer 1

Answer: (C)

It is the resistance of a wire $1cm$ length and $1sq.cm$ cross section

Using $R=\frac{\rho L}{A}$ $⟹$ $\rho =R\frac{A}{L}$

For $L=1$ cm

and $A=1c{m}^2$

$⟹\rho =R$

Specific resistance of the wire is defined as the resistance of the wire $1cm$ length and $1sq.cm$ cross section.