Current, charge and time

Electrical current is defined by how much electric charge has been transferred per second, giving the following relationship:

\[current=\frac{charge}{time}\]

Rearranging this we get:

\[charge = current \times time\]

The symbol for charge is \(Q\), it is measured in coulombs (\(C\)).

The symbol for current is \(I\), it is measured in amperes (\(A\)).

The symbol for time is \(t\), it is measured in seconds (\(s\)).

This gives the relationship:

\[Q = I \times t\]

Example

Question

Calculate the charge that passes through a lamp in 2 minutes if the current is \(1.5A\)?

To calculate the charge, you need to use the following relationship:

\[charge = current \times time\]

Remember to convert minutes into seconds by multiplying by 60

\[Q = 1.5 \times (2 \times 60) = 180C\]