Direct and Alternating Current
The flow of current that you get from a battery is known as direct current or DC.Like the flow of water from a faucet, it is a steady stream, in one direction.
The flow of current that you get from the "hot" wire in a power outlet in your home is
very different. It changes from positive to negative 50 times each second (in Great
Britain and some other nations, 60 times per second). This is known as alternating
current or AC.
Alternating current is essential for some purposes, such as cranking up voltage so that
electricity can be distributed over long distances. AC is also useful in motors and
domestic appliances. The parts of an American power outlet are shown in image
below. A few other nations, such as Japan, also use American style outlets.
For most of this book I’m going to be talking about DC, all laptops motherboards are
powered with DC