U+2130 was added to Unicode in version 1.1 (1993). It belongs to the block Letterlike Symbols in the Basic Multilingual Plane.

This character is a Uppercase Letter and is commonly used, that is, in no specific script. The character is also known as emf (electromotive force).

The glyph is a Font composition of the glyphs E. It has a Neutral East Asian Width. In bidirectional context it acts as Left To Right and is not mirrored. The glyph can, under circumstances, be confused with 38 other glyphs. In text U+2130 behaves as Alphabetic regarding line breaks. It has type Upper for sentence and ALetter for word breaks. The Grapheme Cluster Break is Any.

The Wikipedia has the following information about this codepoint:

Electromotive force, also called emf (denoted and measured in volt), is the voltage developed by any source of electrical energy such as a battery or dynamo. It is generally defined as the potential for a source in a circuit.

The word "force" in this case is not used to mean mechanical force, measured in newtons, but a potential, or energy per unit of charge, measured in volts.

In electromagnetic induction, emf can be defined around a closed loop as the electromagnetic work that would be done on a charge if it travels once around that loop. (While the charge travels around the loop, it can simultaneously lose the energy via resistance into thermal energy.) For a time-varying magnetic flux linking a loop, the electric potential scalar field is not defined due to circulating electric vector field, but nevertheless an emf does work that can be measured as a virtual electric potential around that loop.

In the case of a two-terminal device (such as an electrochemical cell or electromagnetic generator) which is modelled as a Thevenin equivalent circuit, the equivalent emf can be measured as the open-circuit potential or voltage difference between the two terminals. This potential difference can drive a current if an external circuit is attached to the terminals. When this occurs the potential difference between the terminals will fall because of the voltage drop across its equivalent internal resistance.

Devices that can provide emf include electrochemical cells, thermoelectric devices, solar cells and photodiodes, electrical generators, transformers, and even Van de Graaff generators. In nature, emf is generated whenever magnetic field fluctuations occur through a surface. An example for this is the variation in the Earth's magnetic field during a geomagnetic storm, acting on anything on the surface of the planet, like an extended electrical grid.

In the case of a battery, charge separation that gives rise to a voltage difference is accomplished by chemical reactions at the electrodes. Chemically, by separating positive and negative charges, an electric field can be produced, leading to an electric potential difference. A voltaic cell can be thought of as having a "charge pump" of atomic dimensions at each electrode, that is:

A source of emf can be thought of as a kind of charge pump that acts to move positive charge from a point of low potential through its interior to a point of high potential. … By chemical, mechanical or other means, the source of emf performs work dW on that charge to move it to the high potential terminal. The emf of the source is defined as the work dW done per charge dq: = dW/dq.

Around 1830, Michael Faraday established that the reactions at each of the two electrode–electrolyte interfaces provide the "seat of emf" for the voltaic cell, that is, these reactions drive the current. In the open-circuit case, charge separation continues until the electrical field from the separated charges is sufficient to arrest the reactions. Years earlier, Alessandro Volta, who had measured a contact potential difference at the metal–metal (electrode–electrode) interface of his cells, had held the incorrect opinion that contact alone (without taking into account a chemical reaction) was the origin of the emf.

In the case of an electrical generator, a time-varying magnetic field inside the generator creates an electric field via electromagnetic induction, which in turn creates a voltage difference between the generator terminals. Charge separation takes place within the generator, with electrons flowing away from one terminal and toward the other, until, in the open-circuit case, sufficient electric field builds up to make further movement unfavorable. Again the emf is countered by the electrical voltage due to charge separation. If a load is attached, this voltage can drive a current. The general principle governing the emf in such electrical machines is Faraday's law of induction.


System Representation
UTF-8 E2 84 B0
UTF-16 21 30
UTF-32 00 00 21 30
URL-Quoted %E2%84%B0
HTML-Escape ℰ
Wrong windows-1252 Mojibake ℰ
HTML-Escape ℰ
HTML-Escape ℰ
alias emf (electromotive force)
LaTeX \mathscr{E}

Related Characters


  • E
  • ⋿
  • E
  • Æ
  • Œ
  • Ɇ
  • Ε
  • Е
  • Ӕ
  • Ꭼ
  • ℡
  • ℰ
  • ⋿
  • ⴹ
  • ꓰ
  • E
  • 𐊆
  • 𑢦
  • 𑢮
  • 𝐄
  • 𝐸
  • 𝑬
  • 𝓔
  • 𝔈
  • 𝔼
  • 𝕰
  • 𝖤
  • 𝗘
  • 𝘌
  • 𝙀
  • 𝙴
  • 𝚬
  • 𝛦
  • 𝜠
  • 𝝚
  • 𝞔
  • 🄔
  • 🜀


Complete Record

Property Value
Age (age) 1.1
Unicode Name (na) SCRIPT CAPITAL E
Unicode 1 Name (na1) SCRIPT E
Block (blk) Letterlike_Symbols
General Category (gc) Uppercase Letter
Script (sc) Common
Bidirectional Category (bc) Left To Right
Combining Class (ccc) Not Reordered
Decomposition Type (dt) Font
Decomposition Mapping (dm) E
Lowercase (Lower)
Simple Lowercase Mapping (slc) ℰ
Lowercase Mapping (lc) ℰ
Uppercase (Upper)
Simple Uppercase Mapping (suc) ℰ
Uppercase Mapping (uc) ℰ
Simple Titlecase Mapping (stc) ℰ
Titlecase Mapping (tc) ℰ
Case Folding (cf) ℰ
ASCII Hex Digit (AHex)
Alphabetic (Alpha)
Bidi Control (Bidi_C)
Bidi Mirrored (Bidi_M)
Bidi Paired Bracket (bpb) ℰ
Bidi Paired Bracket Type (bpt) None
Cased (Cased)
Composition Exclusion (CE)
Case Ignorable (CI)
Full Composition Exclusion (Comp_Ex)
Changes When Casefolded (CWCF)
Changes When Casemapped (CWCM)
Changes When NFKC Casefolded (CWKCF)
Changes When Lowercased (CWL)
Changes When Titlecased (CWT)
Changes When Uppercased (CWU)
Dash (Dash)
Deprecated (Dep)
Default Ignorable Code Point (DI)
Diacritic (Dia)
East Asian Width (ea) Neutral
Extender (Ext)
FC NFKC Closure (FC_NFKC) e
Grapheme Cluster Break (GCB) Any
Grapheme Base (Gr_Base)
Grapheme Extend (Gr_Ext)
Hex Digit (Hex)
Hangul Syllable Type (hst) Not Applicable
Hyphen (Hyphen)
ID Continue (IDC)
Ideographic (Ideo)
ID Start (IDS)
IDS Binary Operator (IDSB)
IDS Trinary Operator and (IDST)
Indic Positional Category (InPC) NA
Indic Syllabic Category (InSC) Other
ISO 10646 Comment (isc)
Joining Group (jg) No_Joining_Group
Join Control (Join_C)
Jamo Short Name (JSN)
Joining Type (jt) Non Joining
Line Break (lb) Alphabetic
Logical Order Exception (LOE)
Math (Math)
Noncharacter Code Point (NChar)
NFC Quick Check (NFC_QC) Yes
NFD Quick Check (NFD_QC) Yes
NFKC Casefold (NFKC_CF) e
NFKC Quick Check (NFKC_QC) No
NFKD Quick Check (NFKD_QC) No
Numeric Type (nt) None
Numeric Value (nv) NaN
Other Alphabetic (OAlpha)
Other Default Ignorable Code Point (ODI)
Other Grapheme Extend (OGr_Ext)
Other ID Continue (OIDC)
Other ID Start (OIDS)
Other Lowercase (OLower)
Other Math (OMath)
Other Uppercase (OUpper)
Pattern Syntax (Pat_Syn)
Pattern White Space (Pat_WS)
Quotation Mark (QMark)
Radical (Radical)
Sentence Break (SB) Upper
Simple Case Folding (scf) ℰ
Script Extension (scx) Common
Soft Dotted (SD)
STerm (STerm)
Terminal Punctuation (Term)
Unified Ideograph (UIdeo)
Variation Selector (VS)
Word Break (WB) ALetter
White Space (WSpace)
XID Continue (XIDC)
XID Start (XIDS)
Expands On NFC (XO_NFC)
Expands On NFD (XO_NFD)
Expands On NFKC (XO_NFKC)
Expands On NFKD (XO_NFKD)