The two main ways of increasing the current in an electrical circuit are by increasing the voltage or by decreasing the resistance. If you increase the number of lamps in a series circuit ...

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

You can find all of Julian Edgars' series on automotive modifications ... resistance and current (Ohm's Law). This diagram ...