# Viscosity Coefficient

Viscosity coefficient, abbreviated as \(\eta\) (Greek symbol eta), also called coefficient of viscosity, is the tangential friction force required to preserve a unit velocity gradient between two parallel layers of liquid of unit area. The greater the coefficient of viscosity the greater the force required to move the layers at a velocity.

### Viscosity Coefficient Formula

\(\large{ \eta = \frac { F_t \; l } { A \; v } }\)

Where:

\(\large{ \eta }\) (Greek symbol eta) = viscosity coefficient

\(\large{ A }\) = area

\(\large{ l }\) = distance between the layers

\(\large{ F_t }\) = tangential force

\(\large{ v }\) = velocity

Solve for:

\(\large{ F_t = \eta \; \frac { A \; v } { l } }\)