Category: electric power distribution

Where does the exact reversal occur in an alternating current circuit (where doe…

Lou Bloomfield Leave a comment

Where does the exact reversal occur in an alternating current circuit (where does the energy diminish completely and then turn the opposite way)?

The reversal of the current in an alternating current (AC) circuit occurs everywhere in the circuit at once. The whole current gradually slows to a stop and then heads backward. At the moment it comes to a complete stop, the electric power company isn’t supplying any power at all and the circuit isn’t consuming any. Because the power delivery pulses on and off in this manner, devices that operate on AC power are designed to store energy between reversals. Motors store their energy as rotational motion. Stereos store energy as separated electric charge in devices called capacitors, or as magnetic fields in devices called inductors.

If current times voltage equals power, this makes it seem that high current time…

Lou Bloomfield Leave a comment

If current times voltage equals power, this makes it seem that high current times low voltage would equal low current times high voltage; but this is not true because of resistance. How is resistance taken into account in the current times voltage equal power equation?

Your first observation, that high current times low voltage would equal low current times high voltage is true; it means that electricity can deliver the same power in two different ways: as a large current of low energy charges or as a small current of high energy charges. That result is critical to the electrical power distribution system. The resistance problem is a side issue: it makes the delivery of power as a large current of low energy charges difficult. If you could get this current to peoples’ houses without wasting its power, there would be no problem, but that delivery isn’t easy. The wires waste lots of power when you try to deliver these large currents. So the electric power distribution system uses small currents of high-energy charges instead.

Why are there danger signs around high voltage equipment?

Lou Bloomfield Leave a comment

Why are there danger signs around high voltage equipment?

Your body is a relatively good conductor of electricity and it is easily damaged by currents flowing through it. Your body uses electricity to control its functions and an unexpected current of as little as a few hundredths of an ampere can interrupt those functions. In particular, your heart can stop beating properly. Fortunately, your skin is a pretty good insulator so it is hard to get any current to flow through you. But high voltages can push current so hard that it punctures your skin and begins to flow through you. While the current is actually what injures you, the high voltage is what breaks down your protective skin and allows that current to flow through you.