Greek Letters symbol
\etaThe Greek letter eta (\eta) is used in various scientific and mathematical contexts. In physics, it often represents efficiency or viscosity. In mathematics, it can denote a metric or a function, such as the Dedekind eta function in number theory.
Represents efficiency in physics, such as the efficiency of an engine.
\eta = \frac{\text{useful output}}{\text{total input}}Represents dynamic viscosity in fluid dynamics, where F is the force and A is the area.
\eta = \frac{F}{A}The Dedekind eta function, a modular form in number theory.
\eta(\tau) = e^{\pi i \tau / 12} \prod_{n=1}^{\infty} (1 - e^{2 \pi i n \tau})