Final answer:
Capacitance in modern spark plugs is reduced by using a resistor, which decreases interference with electronic devices. The electric field in a capacitor is reduced by a dielectric, which also increases stored energy. Inductors act as low-frequency filters when replacing capacitors.
Step-by-step explanation:
The reduction of capacitance after firing in most modern spark plugs is typically achieved by using a resistor. This resistor serves to decrease the interference with electronic devices that can be caused by the electromagnetic pulse generated when the spark plug fires. To directly address the other information you have mentioned: True or False - The electric field in an air-filled capacitor is reduced when a dielectric is inserted between the plates: This is true. Inserting a dielectric between the plates of a capacitor increases the capacitor's capacitance but reduces the electric field strength for a given charge on the plates. The energy of the system generally increases when a dielectric material is inserted into a capacitor since the dielectric increases the capacitance and thus the energy stored is greater for the same voltage. Replace capacitors with inductors: In the context of filters, an inductor acts as a low-frequency filter (or a high-pass filter) since it resists changes in current that happen quickly, which are characteristic of high-frequency signals. The question about the spark plug current and the defibrillator resistance is complex. For the spark plug, if 200-A current moves 0.300 mC of charge, to calculate the duration of the spark, you would use the formula time = charge / current, which results in a very short duration typical for a spark. As for the defibrillator, the resistance of the path can be determined using Ohm's law, where resistance = voltage / current.