Electric Circuits - Mission EC7 Detailed Help

Three identical light bulbs are connected to a battery as shown below. Which one of the following statements is true?

Current in a Series Circuit:
The overall current in a series circuit is no different than the current in an individual resistor. That is, the current in the battery is the same as the current in resistor 1 or resistor 2 or resistor 3 or ... . Since there are no branching locations, current is never divided and is everywhere the same. The amount of current is related to the voltage (Vtot) impressed across the circuit by the battery and the overall equivalent resistance (Req). In equation form, these ideas can be written as
Itot= I1= I2= I3= ∆Vtot/ Req.

The brightness of a light bulb is dependent upon the resistance of the light bulb and the current in the light bulb. These light bulbs are identical so each bulb has the same resistance. The brightness will then be dependent upon which bulb encounters the greatest current. See Know the Law section.

It is a common belief among Physics students that something is consumed in an electric circuit. The commonly held incorrect idea is that charge or current is used up in an electric circuit. Such students might believe that the current at the beginning of a circuit is much greater than the current at the end of the circuit. But don't be fooled! Current is not consumed. It is everywhere the same. Charge simply moves through the circuit from a high energy location toward the low energy location, everywhere at the same rate.