Why do I experience an electric shock whenever I touch a metal object, especially in the winter time?
Why do I feel electricity shock when I touch a metal in winter?When you move, you generate a static charge by an effect called triboelectric effect.Two objects come into contact, one has a greater affinity for electrons than the other, so that one comes away with more electrons. This has a greater effect on nonconductors, as the charge tends to stay put, then. But one can be a conductor like your body, plus charge can transfer from nonconductive clothing or shoes to your body.Friction is not necessary, but it is an effective way of making and breaking contact between surfaces very quickly. Thanks for the animations from Electro Static Technology, Inc.Electric charge and distance raise the voltage. So you walk around the house, your shoes touching the floor, your clothes rubbing each other and your body, maybe you pet your cat or run a comb through your hair. Then you touch something metal that is grounded, and you discharge in a very high but short current pulse, high enough current so you can feel it and hear the snap.But humidity in the air tends to make the surfaces of conductors leaky insulators, so charge will drain off. It takes at least 5kV before you will even notice the spark. Cold air can’t hold as much moisture as warm air. So your furnace or heater is warming air that was cold, so you end up with very dry warm air. This allows much higher voltages of static charge to build up on you and other things.Artificial fabrics (rayon, polyester, etc.) are excellent insulators and so are the worst offenders. Natural fibers tend to be a bit hygroscopic (moisture friendly) and so aren’t as bad at generating static charge. Dryer sheets and fabric softener prevents static cling by leaving your clothes a little electrically conductive.It is very common these days for manufacturers to add substances to plastic items to make them slightly conductive, to limit the buildup of static charge. Combs and brushes, for instance. When I was a boy, I had to get my comb a little wet before using it, or my hair would stick up like I’d been holding a Van de Graaf generator.Thanks for the image go to Making Electricity! Van De Graaff Generators and Tesla Coils.
Can I fix my vibrating electric mower?
I have a black & decker cordless lawn mower ( http://www.amazon.com/Black-Decker-CM1936-Cordless-Removable/dp/B002YK4UZU/ref=sr_1_1?s=home-garden&ie=UTF8&qid=1306888246&sr=1-1 ) and i hit this stupid metal spike out in the back yard, and now the mower vibrates like crazy. Is this something I can fix myself?
If a residential electric circuit has power entering but all outlets are dead, there has to be a short, right?
After reading many of the replies on this subject I’m going to say concept pretty clear to you to understand the differences between the two. There has been a lot of great advise here as well. Now…the r4eason I’m adding to this is to inform you of 90% of my service calls for this exact problem is a simple “open” in NOT the “hot” or the “energized” side of the circuit but the NEUTRAL wire has lost connection in the back of one of the receptacles in series of the circuit you’re having the problem with. The first comment I saw about replacing the last working plug in series is fantastic advise. Or, using a large, one of the 3 prong plugs from anything (vacuum cleaner or something like that), plugging it in the plugs around the problem circuit and lightly shaking it side to side will find the loose connection on back of that plug. Now, when you’ve found the “problem child”, replace the recept with a new one but don’t wire it the same way you found it….wire it with a ‘pig-tail”. That means, using a 6inch pieces of black, white and the ground wires, “stick” them in the back of the new plug and wire nut all remaining SAME COLOR wires together and carfully place back in the box. I always make them a ‘sweep’ or a wide kind of nice “U” so to keep all the wires around (at least) 6 inches long and neet in the box to not “short” out on any connections.Since the first “problem child” happen, go ahead and go to Home Depot and grab a box of new plugs and change them all. If it happen to one, it’s just a matter of time before the others will follow suit. The box cost only around $11.00 for 10 or the cheaper Leviton ones are $5.80
Why don't birds get electrocuted sitting on power lines?
Current flows in a loop[ which means the circuit is closed]. A bird sitting on a transmission line does not complete the circuit. If the same bird keeps one leg on one line and another leg (or any part of its body) on another line(or the neutral points), then it will get roasted.Consider this circuit where a bird sits on the wire:The values R1 and R2 are resistances of the line. Electricity takes the path of least resistance. The two legs of the bird which is perched on the same line does not complete the circuit. The R_Bird( resistance of the bird’s body) is much higher than that of the line, so the bird might not experience high current. The potential difference between the two legs of the bird is same( since the resistance of the line is the same throughout).The current flows on.The bird is safe.Now consider this scenario:A bird sitting on a line decides to fly away and raises the wings. With one wing touching the neighboring line and the leg on the first line, this creates a closed circuit. Thus electricity (following the path of least resistance) will detect a potential difference between the wing (which touches the other line) and the leg(which is placed on the first line). The current tries to take on that path creating a short-circuit. Eventually the bird gets zapped and falls off the line. Now the current will continue to flow on.The lesson we learn here is that when ever we play with electricity, make sure you (your body) does not close the circuit. When we poke our fingers into an electrical socket we get shocked because our body will offer a lower resistance . Thus a potential difference will be created between your finger and the feet( which is placed on the floor acting as a neutral point).
Why do circuit breakers trip when lightning strikes?
Lightning often strikes power lines, or the protective ground wires above transmission lines. The power company uses special protective devices, called arresters, to safely divert abnormally high voltages to ground before they can cause damage to the power company's equipment. However, the high currents and fast rise-time of some lightning strikes can sometimes result in temporary flashovers of the insulators that normally insulate and support the power lines from grounded poles and towers.Once an electrical arc jumps across the insulator, the electrical power in the lines now has a shorter path (a "short circuit") to ground or to other nearby power (or "phase") lines. The power company uses protective relays that can detect the abnormal current flowing to ground or between phases. The protection relay commands a high-voltage circuit breaker to temporarily remove power to the affected line. Once power is removed, the electrical arc stops, the air recovers its insulating properties, and the short circuit disappears. The protection relay then commands the circuit breaker to reclose a short time later, and normal power delivery is resumed. Downstream customers only see a short loss of power during the time the breaker is open.Sometimes lightning hits a nearby tree, causing a limb to contact a power line, resulting in a short-circuit to ground. As before, the arcing fault is sensed and the circuit breaker is opened briefly, and the breaker then reclosed a short time later. However, when the breaker recloses, if the short circuit is still there, the protection relay will again cause the breaker to open, this time for a somewhat longer period of time. This sequence of opening and reclosing may continue several times, but after a fixed number of retries (set by the power company), the breaker will automatically lock in the "open" position, removing power from that circuit until linemen can remove the problem and manually reset the circuit breaker. In this case, downstream customers will experience an extended power outage.