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)

$7\times {10}^{-2}N/m$

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 $100$cm in $1$cm.
$\therefore \frac{70dynes}{cm}=\frac{70\times {10}^{-5}}{{10}^{-2}}=7\times {10}^{-2}N/m$.