Polarities:

All voltages and currents have polarity as well as magnitude.  Within a series circuit, there is only single current and its polarity is from the negative battery terminal by the rest of the circuit to the positive battery terminal. A Voltage drops across loads also have polarities. The simplest way to search these polarities is to use the direction of the electron current as a basis. Whereas, where the electron current enters the load, the voltage is negative Figure. This holds true regardless of the number or category of loads in the circuit. A drop across the load is opposite to that of the source. A voltage drops oppose the source voltage and decrease it for the other loads.  This is since every load uses energy by leaving less energy for the other loads.