Question

If value of surface tension of a liquid is $70$ dyne/cm, then its value in $N/m$ will be

• A. $7\times 10^{3}N/m$
• B. $7\times 10^{2}N/m$
• C. $7\times 10^{-2}N/m$
• D. $70N/m$

Answer 1

Answer: (C)

The unit dyne/cm is $CGS$ system of unit.
The $CGS$ unit of force is dyne and SI unit is Newton.
Also there are $10^5$ dynes in one newton and $100cm$ in $1cm$.
$\therefore \frac{70\text{ dynes }}{cm}=\frac{70\times 10^{-5}}{10^{-2}}$
$=7\times 10^{-2}N/m$