In series circuits, it is the same current which flows through all parts of the circuit. Therefore the total current flowing in the circuit is the same as that which passes through the first component, the same that passes through the second component and so on.


This can be represented algebraically by the following simple equation:




The size of the current in the circuit to start with will be determined by the potential difference across the circuit and the total resistance of the circuit. This can be shown by the (possibly familiar) equation:



"volts equals amps times ohms"


Underneath the equation I've written a small sentence which should allow you to memorise this quite well. When I was learning physics at this level, it was my physics teacher who taught me this expression and it always stuck in my mind.