# What Is Viscosity?

### What Is Viscosity?

Viscosity is defined as the resistance to flow. This definition will lead to confusion if we take fluids with different densities.

The size and shape of molecules define how viscous the fluid would be.

If we divide the fluid into a number of layers, then the viscosity is the measure of friction between them. For example, Honey is more viscous than Water.

The size and shape of molecules define how viscous the fluid would be.

If we divide the fluid into a number of layers, then the viscosity is the measure of friction between them. For example, Honey is more viscous than Water.

### How is Viscosity Measured?

We can measure the value practically by using Viscometers. The experiment is carried out to count the time in seconds taken by a certain amount of fluid to drain from an orifice hole.

The formula to calculate the value is very simple.

Viscosity = Shear stress / Shear rate

It is expressed in cP (centipoise) units. Starting from water, with viscosity 1cP, most of the other fluids will have positive viscosity value.

At lower temperatures, some fluids will measure zero viscosity and therefore called as 'Mobile Fluids'.

At lower temperatures, some fluids will measure zero viscosity and therefore called as 'Mobile Fluids'.

What Is Viscosity?
Reviewed by Vishwanath Nayak
on
February 06, 2017
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