Question

Why do we use alternating current?

Answer 1

There are two main types of current- direct current and alternating current. Direct current has a constant magnitude and flows only in one direction while the alternating current changes its magnitude and direction periodically with time. The alternating current has many benefits over direct current due to which it is more commonly used.

Complete answer:
Alternating current is the current which periodically changes its magnitude as well as direction with time. Commercially, alternating current is used and supplied to all households. Since, the value of current oscillates between maximum and minimum magnitudes, it is less dangerous than direct current which maintains a constant magnitude and flows only in one direction.
Alternating current is used more commonly because it is easier to transport over longer distances. When AC current is being transported from one place to the other, the voltage is kept very high. We know that, from Ohm’s law,
$R=\dfrac{V}{I}$
Here, $V$ is the voltage
$I$ is the current
$R$ is the resistance
Since, $R$ is constant. At a very high value of voltage, the value of current is minimum and since, the value of current is very less the energy dissipated is minimum.
Also, AC current can be easily converted back from the high voltages using transformers.
Therefore, we use AC current because it is less dangerous, easy to transport and minimum wastage of energy takes place.

Note:
The root mean squared value of AC current is taken as the average value. AC current varies according to a trigonometric function. Transformer is a device which works on the principle of electromagnetic induction and is used to increase or decrease voltage levels.