Question

Surface tension of liquid is $70$ $dyne/cm$. Its value in SI unit is

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

Answer 1

Answer: (B)

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

$1dyne={10}^{-5}N\&1cm={10}^{-2}m$

So, $S=70\frac{dyne}{cm}=\frac{70\times {10}^{-5}N}{{10}^{-2}m}$$=70\times {10}^{-3}N/m$

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