TeXipedia

eta

Represents the Greek lowercase letter commonly used as a variable or parameter in mathematics, physics, and engineering.

Overview

A versatile symbol frequently employed across scientific and mathematical contexts, particularly in:

  • Engineering: Often denotes efficiency in thermodynamics and mechanical systems
  • Physics: Commonly represents viscosity in fluid dynamics
  • Mathematics: Used as a variable in complex analysis and differential equations
  • Statistics: Appears in multivariate analysis and statistical modeling

The symbol's clean, distinctive appearance makes it popular for representing dimensionless quantities and system parameters.

Examples

Using eta to represent efficiency in a thermodynamic equation.

η=WoutQin\eta = \frac{W_{out}}{Q_{in}} 
\eta = \frac{W_{out}}{Q_{in}}

Representing viscosity coefficient in fluid dynamics.

τ=ηdudy\tau = \eta \frac{du}{dy} 
\tau = \eta \frac{du}{dy}

Using eta as a variable in a wave function equation.

Ψ(ξ,η)=Aei(kξ−ωη)\Psi(\xi,\eta) = A e^{i(k\xi - \omega\eta)} 
\Psi(\xi,\eta) = A e^{i(k\xi - \omega\eta)}