Introduction
The current whose magnitude does not change with time is called direct current.
When the magnitude of current changes continuously with time and direction changes periodically it is known as alternating current.
Electric Current
Electric current is defined as the rate of flow of electric charge per unit time through conductor. Electric current is a scalar quantity represented with SI unit Ampere.
- If net charge Q passes through in time interval dt then:
∴ I = dQ/dt
The direction of electric current is taken as the opposite direction of flow of current.
Ohm's Law
Statement: Keeping all the physical conditions constant current through a conductor between two points is directly proportional to the voltage across the two points.
i.e. V ⋉ I
∴ V = IR
[Where R = resistance of conductor]
Current Density
It is defined as the electric current flowing per unit cross sectional area of a conductor it is denoted by 'J'
J = I/A
[∵ Where A is area of the conductor]
It's SI unit is A/m² and it is a vector Quantity.
Drift Velocity
The average velocity gained by electrons in a conducting material due to an electric field
applied is known as drift velocity.
Notes:
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