Question

The $SI$ unit of the coefficient of viscosity is:

• A. $N{s}^{-1}{m}^{-2}$
• B. $Ns{m}^{-2}$
• C. $N{s}^{-2}{m}^{-2}$
• D. $N{s}^{-1}{m}^{-3}$

Answer 1

The correct option is B $Ns{m}^{-2}$

Viscosity is defined as the ratio of the force required to shear a liquid to the velocity of shear (shear means when adjacent layers of liquid are made to slide over each other ).

Coefficient of viscosity,

$\eta =\frac{F}{A\times \frac{dv}{dx}}$

$F$ = tangential force,

$A$ = surface Area b/w the layers

$\frac{dv}{dx}$ = velocity gradient

so $SI$ unit of the coefficient of viscosity is $Ns{m}^{-2}$