When is direct current used

Rising Sea Level. Direct current Figure 1: An animation from a PhET simulation [1] of direct current which has been slowed down considerably. See alternating current for a comparison. NJ: Prentice-Hall, , ch.

Contact us About us Privacy policy Terms of use. One-fourth of a percent is an acceptable loss. Note that if MW of power had been transmitted at 25 kV, then a current of A would have been needed.

This would result in a power loss in the lines of The lower the voltage, the more current is needed, and the greater the power loss in the fixed-resistance transmission lines. Of course, lower-resistance lines can be built, but this requires larger and more expensive wires. If superconducting lines could be economically produced, there would be no loss in the transmission lines at all. But, as we shall see in a later chapter, there is a limit to current in superconductors, too. In short, high voltages are more economical for transmitting power, and AC voltage is much easier to raise and lower, so that AC is used in most large-scale power distribution systems.

It is widely recognized that high voltages pose greater hazards than low voltages. But, in fact, some high voltages, such as those associated with common static electricity, can be harmless. So it is not voltage alone that determines a hazard.

It is not so widely recognized that AC shocks are often more harmful than similar DC shocks. There were bitter fights, in particular between Edison and George Westinghouse and Nikola Tesla, who were advocating the use of AC in early power-distribution systems.

AC has prevailed largely due to transformers and lower power losses with high-voltage transmission. Give an example of a use of AC power other than in the household. Similarly, give an example of a use of DC power other than that supplied by batteries. Why do voltage, current, and power go through zero times per second for Hz AC electricity?

You are riding in a train, gazing into the distance through its window. As close objects streak by, you notice that the nearby fluorescent lights make dashed streaks. Certain heavy industrial equipment uses AC power that has a peak voltage of V.

What is the rms voltage? A certain circuit breaker trips when the rms current is What is the corresponding peak current? Military aircraft use Hz AC power, because it is possible to design lighter-weight equipment at this higher frequency. What is the time for one complete cycle of this power? Another reason that DC generators are more popular is that AC generators require extensive engineering and phase-synchronization equipment placed in series with one another, whereas DC easily lends itself to parallel circuitry.

Daniel R. Mueller is a Canadian who has been writing professionally since Mueller's writing draws on his extensive experience in the private security field. He also has a professional background in the information-technology industry as a support technician.

Much of Mueller's writing has focused on the subjects of business and economics. What Are the Uses of Direct Current? DC Generator Vs. Other than changing the mains AC to DC, most power supplies change the level of the voltage. Most of them will always lower the voltage since most of the electronics functions from much less voltage levels, but higher currents. The laptop adapter must therefore provide a means of lowering the mains voltage from either the V or Volts down to about 20 Volts DC.

DC is used in almost all electronics equipment, electric vehicles, automation, control of electrical equipment, and more. Most office and domestic equipment such as TVs, audio systems, amplifiers, flash lights, computers, tablets and smartphones use DC power to function. However, since the universally available power is AC, the equipment uses an external or internal power supply to convert the utility mains AC into the desired DC for the equipment.