Electric Current: Definition and Direction
Electric current is defined as the rate of flow of electric charge through a cross-section of a conductor, conventionally taken in the direction of positive charge flow.
What is Electric Current: Definition and Direction?
The rate of flow of electric charge through a conductor.
Key formula / rule: Electric Current (Instantaneous)
Key points
- Define electric current.
- State the SI unit of electric current.
- Explain the conventional direction of electric current.
- Relate current to the rate of charge flow.
Common exam trap
Confusing conventional current direction with electron flow direction.
Definitions
- Term
Electric Current
- Meaning
The rate of flow of electric charge through a conductor.
- Term
Ampere
- Meaning
The SI unit of electric current, defined as one coulomb of charge passing a point in one second.
- Term
Conventional Current
- Meaning
The direction of current flow defined as the direction in which positive charges would move, which is opposite to the direction of electron flow in most conductors.
Learning objectives
Define electric current.
State the SI unit of electric current.
Explain the conventional direction of electric current.
Relate current to the rate of charge flow.
Differentiate between conventional current and electron flow.
Formulae
- Name
Electric Current (Instantaneous)
- Note
dQ is the small amount of charge flowing in a small time interval dt.
- Expression
I = dQ/dt
- Name
Electric Current (Average)
- Note
\Δ Q is the total charge flowing in time interval \Δ t.
- Expression
Iavg = \Δ Q / \Δ t
Prerequisites
Concept of electric charge
Understanding of conductors and insulators
Basic understanding of motion and rate
Common mistakes
Confusing conventional current direction with electron flow direction.
Incorrectly applying the formula I = dQ/dt without considering the time interval.
Assuming current is always in the direction of electron movement.
Keywords
Electric Current
Charge Flow
Ampere
Conventional Current
Electron Drift
Rate of Charge
Practice preview
In a metallic conductor, the charge carriers responsible for electric current are:…
medium
The conventional direction of electric current is taken to be the direction of flow of:…
easy
If 5 Coulombs of charge pass through a conductor in 2 seconds, what is the electric current flowing through it?…
medium