ESU of current to Gaussian electric current
ESU
G cgs
Conversion History
| Conversion | Reuse | Delete |
|---|---|---|
1 ESU (ESU of current) → 1.00000001498962230569 G cgs (Gaussian electric current) Just now |
Quick Reference Table (ESU of current to Gaussian electric current)
| ESU of current (ESU) | Gaussian electric current (G cgs) |
|---|---|
| 1 | 1.00000001498962230569 |
| 10 | 10.0000001498962230569 |
| 100 | 100.000001498962230569 |
| 1,000,000 | 1,000,000.01498962230569 |
| 1,000,000,000 | 1,000,000,014.98962230569 |
| 3,000,000,000 | 3,000,000,044.96886691707 |
About ESU of current (ESU)
The electrostatic unit of current (ESU, also called the statampere) equals approximately 3.335641×10⁻¹⁰ amperes. It is the current unit of the CGS electrostatic system (CGS-ESU), in which Coulomb s law is written without a permittivity constant and electromagnetic quantities are derived from the statcoulomb (franklin). One statampere is the flow of one statcoulomb per second. The factor 3.336×10⁻¹⁰ arises because 1 A = (c/10) ESU, where c ≈ 3×10¹⁰ cm/s is the speed of light in CGS units. The CGS-ESU system was used in early electrostatics and vacuum tube physics but is entirely obsolete in applied engineering.
1 ESU of current ≈ 3.336×10⁻¹⁰ A — an extraordinarily small current. One ordinary ampere equals approximately 3×10⁹ ESU.
About Gaussian electric current (G cgs)
The Gaussian unit of electric current equals approximately 3.335641×10⁻¹⁰ amperes, derived from the Gaussian CGS system in which the speed of light c enters electromagnetic relations explicitly rather than through permittivity or permeability constants. One Gaussian current unit equals one statampere — one statcoulomb per second — and the SI conversion is I_SI = I_Gaussian × c_cm/s / 10, where c ≈ 2.998×10¹⁰ cm/s. The Gaussian system remains common in theoretical and computational physics, plasma physics, quantum electrodynamics, and astrophysics literature where its symmetric treatment of electric and magnetic fields simplifies equations.
1 Gaussian current unit ≈ 3.336×10⁻¹⁰ A. Plasma physics and astrophysics papers routinely quote electromagnetic quantities in Gaussian units rather than SI.
ESU of current – Frequently Asked Questions
Why is the ESU of current so absurdly small compared to an ampere?
The ESU system was designed to make Coulomb's electrostatic law simple (no constants), which means its charge unit (the statcoulomb) is tiny relative to the coulomb. Since current is charge per time, the statampere inherits that smallness. One ampere is about 3 billion statamperes — the speed of light (in cm/s) divided by 10 shows up in the conversion.
What is a statampere and is it the same as an ESU of current?
Yes, the statampere and the ESU of current are exactly the same unit: approximately 3.336 × 10⁻¹⁰ A. "Statampere" is the named form; "ESU of current" is the descriptive form. The "stat-" prefix comes from "electrostatic," just as "ab-" prefix in the EMU system comes from "absolute."
What role did the ESU system play in the discovery that light is electromagnetic?
When Weber and Kohlrausch measured the ratio of ESU to EMU charge in 1856, they got a number suspiciously close to the speed of light — about 3×10¹⁰ cm/s. Maxwell realized this was no coincidence: it meant electromagnetic disturbances propagate at light speed, proving light itself is an electromagnetic wave. A unit conversion exercise led to one of the greatest discoveries in physics.
What practical problem did the ESU system solve for 19th-century telegraph engineers?
Telegraph cables behaved like long capacitors — charge stored along the line distorted signals over transatlantic distances. The ESU system, built around Coulomb's law, made capacitance calculations straightforward: no permittivity constants, just geometry and charge. William Thomson (Lord Kelvin) used ESU-based analysis to diagnose and fix signal distortion on the first transatlantic telegraph cables in the 1860s.
Why were electrostatic and electromagnetic measurements historically done in separate labs?
Electrostatic experiments (rubbing rods, Leyden jars, spark gaps) involved high voltages and tiny charges, while electromagnetic work (coils, galvanometers, telegraph lines) involved low voltages and large currents. The equipment, techniques, and even the physicists were different. Each community built units natural to their measurements — ESU for electrostatics, EMU for electromagnetics — and it took decades after Maxwell to unify them into one coherent SI framework.
Gaussian electric current – Frequently Asked Questions
Why do astrophysicists prefer Gaussian units over SI?
In Gaussian units, electric and magnetic fields have the same dimensions, and Maxwell's equations look more symmetric — no ε₀ or μ₀ cluttering the formulas. When you study electromagnetic radiation in vacuum (starlight, cosmic rays, pulsar emissions), this symmetry is physically meaningful and simplifies calculations considerably.
What makes Gaussian CGS different from pure ESU or EMU?
Gaussian is a hybrid: it uses ESU conventions for electric quantities (charge, electric field, current) and EMU conventions for magnetic quantities (magnetic field, flux). This cherry-picking gives clean equations for both electrostatic and magnetic phenomena, at the cost of the speed of light appearing explicitly in equations linking electric and magnetic fields.
What happens to the fine-structure constant when you switch from SI to Gaussian units?
In SI, the fine-structure constant α = e²/(4πε₀ℏc) ≈ 1/137. In Gaussian units, ε₀ disappears and α simplifies to e²/(ℏc) — cleaner and more physically transparent. This is one reason particle physicists and quantum electrodynamics theorists favor Gaussian: fundamental constants combine more naturally, and the coupling strength of electromagnetism is immediately visible as α ≈ 1/137.
How do Gaussian units make Maxwell's equations look more elegant?
In Gaussian CGS, Maxwell's equations replace ε₀ and μ₀ with explicit factors of c, and the electric field E and magnetic field B end up with the same dimensions. The symmetric form ∇×E = −(1/c)∂B/∂t and ∇×B = (1/c)∂E/∂t reveals that E and B are equal partners in electromagnetic waves — a physical insight that SI's asymmetric constants obscure.
Why does Jackson's Classical Electrodynamics textbook use Gaussian units?
J.D. Jackson chose Gaussian units because they reveal the deep symmetry between electric and magnetic fields and make relativistic electrodynamics equations cleaner. His textbook, used in virtually every physics PhD program since 1962, cemented Gaussian as the "language" of theoretical electromagnetism. Later editions added SI appendices as a concession to modernity.