Electric current is defined as the amount of charge flowing through a conductor in a unit time. Basically, it is just the flow of electrons under the influence of an electric field. It is represented by the formula- \[I=\frac{Q}{t}\]
The direction of current is always taken from positive terminal of the battery to the negative terminal of the battery.
Current in a conductor can also be represented by the formula-
\[I=Ane{{v}_{d}}\]
where, A = area of cross-section of the conductor
n = number of free electrons
e = charge on an electron
${{v}_{d}}$ = drift velocity of electrons
where, I = current
Q = charge flowing through the conductor
t = time in seconds
Current in a conductor can also be represented by the formula-
\[I=Ane{{v}_{d}}\]
where, A = area of cross-section of the conductor
n = number of free electrons
e = charge on an electron
${{v}_{d}}$ = drift velocity of electrons
Drift velocity is defined as the velocity which an electron attains due to an electric field.
What causes the movement of electrons?
When potential difference is applied across a conductor, an electric field is set up, which causes the movement of electrons.
The positive charges developed across the end A of the conductor attracts the electrons, thus setting up a current which is opposite to the direction of movement of electrons.
TYPES OF CURRENT
There are two types of current-
- DC current
- AC current
DC current-
DC stands for Direct Current. This type of current in only one direction. It is produced by sources such as batteries, thermocouple, solar cells, etc.
AC current-
AC stands for alternating current. In AC, the movement of electric charges periodically reverses its direction. This means that the polarity of AC source changes periodically. The usual waveform of an AC power circuit is a sine wave. In general, AC form is more widely used than DC. Mostly, AC is generated and transmitted for all industrial, commercial and residential uses. But, in some places DC is required in place of AC.
Unit used-
Current is usually measured in Amperes. This unit of current was named after the famous scientist Andre Marie Ampere. Symbolically, it is written as capital 'A'. The magnitude of current can be measured by an instrument called Ammeter.
For example, 1A, 2A, 20A, etc.
MAIN EFFECTS OF ELECTRIC CURRENT-
The three main effects of electric current are-
- Magnetic effect
- Chemical effect
- Heating effect
- Magnetic effects: Bells, relays, motor, generator, transformer, telephones, car ignition and lifting magnets.
- Chemical effect: Primary & secondary cells and electroplating.
- Heating effect: Cookers, water heaters, electric fires, irons, furnaces, kettles and soldering irons.
