# Electrical Charge and Current

## Electrical Current

**Electric current** is *the flow of electric charge*. The size of the current is the rate of flow of electrical charge. Electric charge is carried by electrons. In order for electric current to flow through a circuit, a source of potential difference (like a battery or a cell) must be included.

## Current Equation

You must be able to remember and apply this equation:

Charge flow = current x time

This can also be written as:

Q = Charge (Coulombs, C)

I = Current (Amps, A)

t = Time (Seconds, s)

Around a single loop the current always remains the same.

Let’s look at some examples:

Notice, in the second example, time is changed from minutes to seconds. **Always use seconds!!** Never minutes or hours.

Also, look at the three steps in showing ones working. You should always show your working, even if you use a calculator - and never forget to include units!

- What is the unit of Charge?
- Your answer should include: Coulombs / C
- Calculate the charge which passes a point in a circuit with a current of 10A in 45 seconds.
- Your answer should include: 450C / 450