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Answers:AC alternates - so the current naturally passes through zero twice very cycle. Interruption in an AC circuit breaker takes place at one of those natural current zeros. There is arcing during the course of interruption - dielectric strength builds up gradually as the breaker contacts physically open, and until the contacts have opened sufficiently, conduction will re-establish after the initial currents zeros. But once the contacts are open sufficiently to provide enough dielectric strength, the arc will be extinguished. The breaker mechanism may include provides to accelerate arc extinction - typical scheme include arrangements that extend and cool the arc. DC does not alternate, so there are no natural current zeros. That implies two things. First, the physical opening of the breaker must be faster and physically greater to create sufficient dielectric withstand to extinguish the arc. That is usually what is done with smaller breaker. But for breakers with larger electrical ratings, it may be necessary to include a provision to force an artificial current zero. One approach is to include a capacitor that is charged by the normal DC voltage, and that is inserted into the circuit as the breaker opens to oppose the normal voltage to force the current to zero.
Answers:The source of energy. In a DC circuit, the source of energy provides a constant voltage to the circuit. In an AC circuit, the source of energy provides a varying voltage to the circuit, usually varying sinusoidally with time, causing an alternating current in a pure resistive load.
Answers:Alternating current (ac) reverses the flow of electrons 60 times per second and can be used in transformers to increase or reduce voltage. Most homes have single phase current (110 volts) for lights, radios, microwave ovens, etc.) and two phase current (220 volts) for electric stoves, central air conditioning, and clothes dryers, etc.). Direct current (dc) is usually obtained in the home using batteries at about 1.5 volts per cell, but can be placed in series (as in a flashlight) to add cell voltages. Most vehicles us 12 volt batteries. Because the voltage of batteries is generally much less than ac sources it is much safer if accidentally touched. However, high dc voltages of perhaps 110 volts would be more dangerous than 110 volt ac because dc current tenses muscles in one direction and if a dc wire is grabbed it may not be possible to let go. Many dc batteries use heavy metals (cadmium, etc.) that are highly toxic and must be disposed of correctly. In some jurisdictions retailers who sell toxic batteries must also accept them for proper disposal to prevent contamination of groundwater flowing away from dumps.
Answers:RC - Roman Catholics AC - Anglo Catholics DC - Doomsday Catholics They are not compatible with each other and they will blow up if you join these circuits together. Most explosive is the DC