An electric current is the rate of flow of electric charge past a point or 
region.However, current direction is defined, by convention, as the direction 
of movement of positive charge and therefore both holes and electrons 
contribute to current flowing through the conductor in the hole direction.Direct current may flow 
through a conductor such as a wire, but can also flow through 
semiconductors, insulators, or even through a vacuum as in electron or ion 
beams.It can also be carried by ions in an electrolyte, or by both ions 
and electrons such as in an ionized gas (plasma).At normal temperatures current will flow through a conductor if a battery 
is connected across it. Substances that let electric charge easily flow through 
them are called conductors.The electric current flows in a constant direction, distinguishing it 
from alternating current (AC).In electric circuits this charge is often carried by electrons moving 
through a wire.Electrons, being negative, will be attracted towards the positive side of the 
battery while holes (i. e. positive charge carriers) will move in opposite 
direction.Direct current (DC) is the unidirectional flow of an electric charge.The SI unit of electric current is the ampere, which is the flow of electric 
charge across a surface at the rate of one coulomb per second.Electric current is measured using a device 
called an ammeter.One of the best-known conductors is copper.The ampere
(symbol: A) is an SI base unit.A battery is a prime example of d.c. power.