Question

Surface tension of liquid is $70\text{dyne/cm}$. Its value in $\text{SI}$ is

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

Answer 1

The correct option is B $7\times {10}^{-2}\text{N/m}$

As we know that $1\text{N}={10}^5\text{dyne}$ and $1\text{m}=100\text{cm}$
Putting the values we have surface tension in $\text{SI}$ as
$\frac{70\times {10}^{-5}\text{N}}{{10}^{-2}\text{m}}=7\times {10}^{-2}\text{N/m}$