Alternating Current
This is known as a direct current or DC. The two major types of currents are AC (alternating current) and DC (direct current). In AC the charges move back and forth, but in DC the charges flow in JUST ONE DIRECTION. Due to this characteristic it will not reverse direction like AC can.
Direct current does not reverse direction
direct current
You can reverse the direction of the magnetic field by reversing the direction of the electrical current.
direct current
direct current
Direct.
Reverse the current. :D
It is called an alternating current
Alternating current would fit this description.
Cooling fans use electric motors which operate by magnetism. As the direction of the current flow reverse, the magnetic poles reverse and hence the change in direction.
The magnetic field reverses direction.