Electricity - Electric Current

Question 1

What is Electric Current?

Answer 1

• An electric current is a flow of electric charge
• The formula for Electric Current is:
Current = Charge / Time
• The standard unit for electric current is the amp, and amp is one coulomb of charge per second.

Question 2

Current in Circuits

Answer 2

• Current in metal wires is usually carried by electrons.
• Each electron carries the same quantity of charge (1.602 * 10^-19)
• Current flow has a direction: the conventional current is defined as the direction of flow of positive charges.
• Some electric circuits use a direct current (DC), which always has the same direction. Others use alternating current (AC) whose direction switches back and forth
• Electric current through a component can be measured by an ammeter connected in series with the component.

Question 3

Charge Carriers

Answer 3

• It is not just electrons that can carry current - any flow of charged objects makes an electric current
• In electrolytes, current is carried by both positive and negative ions
• If a potential difference is applied, the positive ions will be attracted to the lower electric potential whereas the negative ions will be attracted to the higher electric potential.
• The principle behind electrolytic and voltaic cells is that a circuit is formed that includes a current of positive and negative ions in the cell, and electrons outside the cell. Depending on the electrochemical reactions taking place, this either requires or releases energy.