A DC circuit, or a direct current circuit, is a circuit with a single flow of electric charge coming from a source. The DC circuit has to have a coulpe of things to properly work though. First of all it has to have a source to produce the voltage such as a battery or a wall outlet. The voltage then provides energy for the current. Another element it has to have is a conductor to transfer the electrical charge from one point to another, such as a wire.
Series
In this circuit there are 1 battery powering the two lightbulbs. The voltage is fed into the circuit by the battery. The batteries hold the energy that goes through the entire circuit which lights up the lightbulbs since they are part of the circuit. If either light bulb were removed in the circuit then the other light bulb would go out because the ciruit would not be complete. The role of resistance is to define the voltage and the current. The voltage in each lightbulb compared to the battery is the total voltage divided by the number of resistors if they have the same resistance which in this diagram they are.
Complex
In this circuit there are two lightbulbs in series and two other light bulbs in parralell. The voltage is the same for the two lightbulbs that are just in series because they have the same resistance and the same current. Also the two lightbulbs in parrallel would have the same voltage and current because of their same resitances,but their currents and voltages would be different from the ones in series. If you removed one of the light bulbs in series then the entire circuit would go out but if you removed one of the bulbs in parrallel then the circuit would still be running.
Parallel
In this circuit the two lightbulbs are in parrallel so that means that the current goes through two differnt paths to get to the series part of the circuit. The current of the two lightbulbs are the same since they have the same resitance and voltage. The voltage is provided by the battery which has stored energy in it. Even if one bulb is removed then the other will still be lit because they are not in one complete series. The role of resistance in the parrallel circuit is to measure the current and voltage and to slow down the current.
