I do not agree with the "answer" below. What do you think about it? Question: When you turn the key in an automobile, you complete a circuit from the negative terminal through the electric starter and back to the posstive battery terminal. This is a DC circuit and electrons migrate through the circuit in a direction from the negative battery terminal to the posstive terminal. About how long must the key be in the ON position for the electrons starting from the negative terminal to reach the positive terminal? a) Atime shorter than that of the human reflex turning a switch on or off. b)1/4 seconds c/4 seconds d)4 minutes e)4 hours. The answer: is e Although the electrical signal travels through the closed circuit at about the speed of light, the actual speed of electron (drift velocity) is much less. Although electrons in the open circuit (key in OFF position) at normal temperatures have an average velocity of some millions of kilometers per hours., they produce no current because they are moving in all possible directions. There is no net flow in any preferred direction. But when the key is turned to the ON position, the circuit is completed and the electric field between that battery terminals is directed through the connecting circuit. It is this electric field that is established in the circuit at about the speed of light. The electrons all along the circuit continue their random motion, but are accelerated by the impressed electric field in a direction toward the end of the circuit connected to the positive terminal. The accelerated electrons cannot gain appreciable speeds because of collisions witht eh anchored atoms in their paths. These collions continually interrupt the motion of the electrons so that their net average speed is extremely slow--less than a tiny fraction of a centimeter per second. So some hours are require for the electrons to migrate from one battery terminal through the circuit to the other terminal.