Eta (Η, η)
Quick Info
- Pronunciation: AY-tuh
- English: ē
- Common Use: Efficiency
Historical Background
Seventh letter of the Greek alphabet, derived from Phoenician letter "heth". The name comes from the Phoenician word for fence or enclosure, reflecting its original pictographic representation of a barrier or boundary.
Scientific Applications
Physics
Efficiency
Fluid Mechanics
Dynamic viscosity
Mathematics
Dedekind eta function
Quantum Mechanics
Dirac notation
Symbol Codes
Unicode
Uppercase
- Code: U+0397
- Hex: Η
- Decimal: Η
Lowercase
- Code: U+03B7
- Hex: η
- Decimal: η
HTML
Uppercase
Η
HTML entity for uppercase Eta
Lowercase
η
HTML entity for lowercase eta
LaTeX
Uppercase
\Eta
LaTeX command for uppercase Eta
Lowercase
\eta
LaTeX command for lowercase eta
Common Usage
Engineering
Thermal Systems
Thermal efficiency in engines
Power Generation
Generator efficiency
Energy Conversion
System performance
Physics
Fluid Dynamics
Dynamic viscosity
Quantum Mechanics
Wave functions
Optics
Optical efficiency
Mathematics
Number Theory
Dedekind eta function
Complex Analysis
Modular forms
Special Functions
Series expansions
Common Applications
Thermodynamics
Carnot efficiency
Cycle efficiency
Compressor efficiency
Fluid Mechanics
Newton's viscosity law
Viscosity-temperature relation
Reynolds number
Special Applications
Mathematical Functions
Dedekind eta function
Discriminant function
j-invariant
Engineering Systems
System efficiency
Pump efficiency
Motor efficiency
Engineering Applications
Power Systems
- • Generator efficiency
- • Transmission losses
- • Power conversion
- • Energy transfer
Heat Engines
- • Thermal cycles
- • Heat exchangers
- • Combustion systems
- • Refrigeration
Fluid Systems
- • Pump performance
- • Pipe flow
- • Viscous effects
- • Flow resistance
How to Type Eta
Windows
Alt Code
- Hold Alt
- Type 951 for η
- Release Alt
Character Map
- Open Character Map
- Select Greek
- Find and copy Eta
Unicode
- Hold Alt + X
- Type 03B7
- Release Alt + X
macOS
Option Key
- Press Option + h for η
Character Viewer
- Press Control + Command + Space
- Select Greek
- Click Eta
Linux
Compose Key
- Press Compose + h + h for η
Unicode
- Press Ctrl + Shift + U
- Type 03B7
- Press Enter
Frequently Asked Questions
What is the difference between Eta (Η) and Latin H?
While they look identical in uppercase form, Eta and Latin H have different historical origins and uses. Eta is primarily used in Greek text and scientific notation, particularly for efficiency and viscosity.
How is eta used in engineering?
In engineering, η (eta) commonly represents efficiency, particularly in thermal and mechanical systems. It's used to calculate the ratio of useful output to total input energy or work.
What is the Dedekind eta function?
The Dedekind eta function η(τ) is a mathematical function important in number theory and the theory of modular forms. It's defined using infinite products and has connections to partition functions.
Why is eta used for viscosity?
η is traditionally used to represent dynamic viscosity in fluid mechanics. This usage dates back to early work in fluid dynamics and has become standard notation in the field.
Writing Guidelines
Uppercase resembles the Latin H, lowercase has a distinctive n-like shape with a longer right stem. In handwriting, ensure the lowercase η is clearly distinguished from the Latin n and the Greek nu (ν).