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19 Questions around this concept.
The charge flowing in a conductor changes with time as . Where
and
are constants. The minimum value of the current is :
The value of current i in the circuit shown in figure is
A wire carries a current of 2.0 A. What is the charge that has flowed through its cross– section in 1.0 s. How many electrons does this correspond to?
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Definition: Electric current is defined as the rate of flow of electric charge through any cross-section.
i.e If a charge of flows through an area for time
then
average electric current through the area is defined as
The instantaneous current at any time t is given by
And If the flow is uniform then Current
If a current I flows through an area for time t then, total charge flowing is
As Current is the rate of flow of charge, Charge can be +ve or -Ve.
The direction of flow of positive charge is considered as the conventional direction of current .
Or the direction opposite to the direction of flow of negative charge is considered as the conventional direction of the current .
For a closed circuit
Conventional current: Positive terminal to negative terminal
Electron current: Negative terminal to Positive terminal
Current can be added algebraically.
Unit of Electric Current: The unit of electric current is Ampere or A.
The current is said to be 1 ampere when 1 coulomb of charge flows through any cross-section in every second.
Calculating current in different situation-
When charge is performing translatory motion
If particles each having charge
pass a given area in time
When charge is performing rotatory motion
If a point charge q is moving in a circle of radius r
With Velocity V (frequency , angular speed \omega and time period T)
Then
Types of current
Alternating current
Magnitude and direction both varies with time.
Shows heating effect only.
Its symbol
Direct current
No change in magnitude and direction with time.
Shows heating effect , chemical effect and magnetic effect of current.
It's a symbol
Current independent of Area-
Current does not change with change in cross-sectional area
Here
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