## 27/06/2021

### Electric Current, Unit of Current

• The electrical current is defined as the rate of flow of charge in particular direction.

OR

• It is defined as the net flow of charge that passes through any cross-sectional area in a unit time.

I = Q / t

I = dQ / dt

Where

I = Current

Q = Charge

t = Time

• In earlier time, it was thought that the current is flows due to positive charge when electrons were not known.
• It was realized that the electrons are responsible for flow of current after discovery of electrons.
• The direction of positive charge from positive terminal of battery to negative terminal is taken as the direction of the conventional current.
• We can say that the direction of conventional current is opposite to the direction of electrons.
• The direction of electrons as conventional current is shown in the figure.

### One ampere current

• If a one coulomb of charge flows through conductor in a one second, the electrical current flowing through conductor is called as one ampere.

### Unit of current

I = Q / t

• The SI unit of charge is coulomb and time is second therefore the SI unit of current is charge / second or ampere.
• 1 mA = 10 – 3 ampere
• 1µA = 10 – 6 ampere
• 1nA = 10 – 9 ampere

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