hieee.........friends i have some useful information to share .......plz see it
1) Why is electricity visible in sparks, but invisible when it's inside the wires?
A spark is not electricity.
A spark is NITROGEN/OXYGEN PLASMA. Plasma is related to fire. The plasma is created when some high voltage is present. High voltage causes air molecules to be torn apart, and as they hit other molecules or fall back together, they give off light. Plasma is conductive, so once it has formed between two wires, it joins the wires together electrically, and charges can flow through it. It might SEEM as if "electricity" has jumped through the air. In reality, a glowing "wire" has formed, and this "wire" is made of plasma. We can only see the plasma jump between the ends of the wires. We cannot see the flowing charges or the electrical energy.
2) Why does the electric company bill us, since it takes back all of the electrons it gives us?
The electric company does NOT sell electrons. Instead, it only pumps electrons. It pumps the movable electrons which fill the wires. The electrons are provided by the atoms of the copper. You pay for a pumping service!
3)When electricity is sent to homes, how does it 'know' if no appliances are connected? Does it go back to the generators again?
Great question!
Whenever the electric company sends electromagnetic energy to your home, and when you don't have any appliances plugged in, something interesting occurs. The energy bounces! It reflects from the open ends of the wires and travels back to the big generators, where it's automatically used to keep them spinning. Because this occurs, the generators won't slow down much. And that means the electric company won't have to burn much fuel at all to keep the giant rotors going. But if you turn on all your lights and run all your appliances, then some of the energy stops bouncing when it gets to your house. The big generators start to slow down, so more fuel must be burned to run the steam turbines which keeps the rotors going at their original speed.
Here is another way to say the same thing:
If you unplug all of your appliances, less energy gets used.
Whenever you plug in a light bulb, the electric company's generators feel it almost instantlu. They feel the extra friction (the electrical friction, not mechanical). Your light bulb uses up some energy, and this means that some of the energy DOESN'T get reflected back to the generators. As a result, the generators start to slow down a bit, and more fuel must be burned in order to prevent this. By turning on a light bulb, you can cause a distant nuclear reactor to eat more U-235, or cause a coal-fired boiler to grind up a bit more coal into powder for burning.
On the other hand, when you suddenly turn off a light, you create a "dead end" in the energy system. The energy that was sent to your home starts being reflected back to the big generators, and it makes them spin a tiny bit faster. The electric company must then turn down the fires which run the steam turbines to keep the generators from speeding up. They do this quickly, and the changes in generator speed are extremely tiny.
4) The liquid between a baterry's plate is a good conductor, so why doesn't it short out the battery ??
Batteries are chemically-powered charge pumps which create voltage. The location of the charge pump is on the surface of the battery plates. All batteries contain two charge pumps: one on each plate. These are called the " half-cell reaction sites."
In other words, even a single dry cell actually contains two separate "cells." These cells are wired in series, so their voltages add together. The surfaces of the metal plates act as the true energy-producing "batteries." The conductive liquid acts as a wire. It connects these two "batteries" together.
So, rather than being a short circuit, the conductive liquid is part of the battery's internal "wiring," it's part of the complete circuit.
If you really wanted to "short out" the innards of a battery, you would have to somehow disrupt the thin surface layers of the battery plates. If part of those layers were destroyed, this would let the charges on one side of the charge-pump go directly to the other side without having to flow through the battery's outside terminals. (And this is one reason that batteries have a "shelf life;" it's because part of the battery plates stop acting like charge pumps, and in that case some charge does leak backwards across the pump, causing the battery to eventually go dead. )
5) why can't batteries electrocute people ??
They can! But you'd need lots of batteries. Single electric cells are very safe.
Everyday batteries are safe because their voltage is so low.
electrocution is not just caused by electric current. Instead it is caused by an electric current inside your body. Currents themselves are not dangerous as long as the path for current is through a wire! Voltage is important here, but voltage is not dangerous unless it causes a current INSIDE your body.
Human skin is electrically conductive, but it is not a good conductor. It takes about 40 volts of electrical "pressure" in order to create a dangerous electric current inside your flesh. 40 volts is the "danger voltage." Anything higher than 40V can shock you. Fortunately, most batteries are way below 40 volts (most are below 12 volts.) Batteries lack the pumping-force needed to create dangerous currents in humans.
Batteries CAN electrocute people if you connect a large number of batteries in series.
Batteries CAN electrocute people if the path of the current somehow goes through your skin. For example, if you made some big bloody cuts in your hands, then even a 6V flashlight battery might kill you if you placed those cuts against the battery terminals.
Back to Community Shelf
10 Nickels awarded!![[Post New]](/templates/default/images/icon_minipost_new.gif){kind=icon}
176
