Electric current
Current measures charge crossing a chosen surface per unit time.
Key knowledge
Electric current is the signed rate of electric charge passing through a specified cross-section. Its SI unit is the ampere, equal to one coulomb per second.
Values and equations
I = dQ/dt; I_average = ΔQ/Δt
- I
- Signed current through the cross-section A
- Q
- Signed charge transported through that cross-section C
- t
- Time s
Conditions and scope
- Specify a positive crossing direction.
- Conventional current follows positive-charge motion; electron drift can be opposite.
Sources · 5
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
- University Physics, volume 2: Electrical CurrentSamuel J. Ling, Jeff Sanny and William Moebs / OpenStax, Rice UniversityTextbook chapter
Bureau International des Poids et Mesures (BIPM)2 sources
- Current Electricity · Physics (2026–27 reprint)National Council of Educational Research and Training (NCERT)Textbook chapter · PDF
- 国際単位系(SI)第9版 · Japanese translation, V3.01National Metrology Institute of Japan, AISTReference guide · PDF
Evidence and review
OpenStax 9.1, average/instantaneous current and charge direction; SI Brochure Table 4, coulomb = A s.
2026-10-10 · Charge-flow definition and SI unit only; no conductivity model is assumed.
Foundational review
2026-10-10 · Fresh primary-source inspection of the complete compact record, including every statement, equation, quantity and material condition, followed by independent AI editorial review. This check does not certify all linked lessons or every passage of every cited publication.
Sources from other places
Scope or convention differs
Signed current is the time rate of charge crossing a surface; conventional direction is opposite electron drift, with A=C/s.
The current derivation agrees. The school chapter’s older force-based ampere definition is superseded by the exact elementary-charge definition.
National Council of Educational Research and Training (NCERT)
- Current Electricity · Physics (2026–27 reprint) IndiaEnglish
3.2 equation3.2; 3.3 conductor charge direction
- Current Electricity · Physics (2026–27 reprint)
National Metrology Institute of Japan, AIST
- 国際単位系(SI)第9版 · Japanese translation, V3.01 JapanJapaneseShared standard
2.3.1 Ampere, printed pp16–17
- 国際単位系(SI)第9版 · Japanese translation, V3.01
Entry details
Permanent link to this entry ↗- Record identity
- physics-electric-current
- Revision
- core.1
- Structured reference record
- Essential core · first collection