fluorescent lights (like compact fluorescent lights or CFLs) or white LED lights, which use up less energy and last longer (but often cost more upfront).
ALTERNATING CURRENT AND DIRECT CURRENT Direct current involves the flow of electric charge in just one direction. This is not the kind of electricity seen in common electrical situations, which involve alternating current. Alternating current or AC is the periodic reversal of direction. This will be a sinusoidal flow of electricity that is typical of the power sources one sees in homes and businesses. In such cases, the electrical voltage will flow in a wave-like pattern that has a certain frequency in Hertz. The voltage will be in phase with each other. In an AC current, the light actually flickers at around 120 times per second; however, you cannot detect that. Sometimes, it can be detected with a fluorescent bulb. The power will always be fluctuating with the power equal to the amps times the voltage. There will always be power but the current changes direction with an average power being one-half multiplied by the voltage multiplied by the amps. The RMS current and the RMS voltage are the root-mean-square current and the root-mean-square voltage, respectively. These are averages that are quoted when talking about electricity and electrical items you normally think of. Why is AC used rather than DC? Power is sent from long distances—from large electric plants to one’s homes and businesses. It’s important that the energy losses get minimized during transfer. High voltages can be transmitted with much smaller power losses than low voltages. Because one doesn’t need such high voltages in the home, it is decreased, partly for safety reasons. It is much easier to increase and decrease AC voltages than DC voltages. This is why AC voltages are used. Transformers will step up the voltages at the power plant and decrease them at the point of use.
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