Which of the following scenarios will cause the current to stop flowing within a circuit?
a. insulating materials within the circuit are replaced with conducting materials.
b. a wire connected to the voltage source runs from the negative to the positive terminal.
c. the switch within the closed circuit is opened.
d. the circuit is closed.

Students in an introductory physics lab are performing an experiment with a parallel-plate capacitor made of two circular aluminum plates, each 11 cm in diameter, separated by 1.0 cm. how much charge can be added to each of the plates before a spark jumps between the two plates? for such flat electrodes, assume that value of 3×106n/c of the field causes a spark.