Q:I'm a physics students and often come up with seemingly stupid questions I can't really find an answer to. If the human body acts as a resistor of around 100 kilo-ohms or more, how is it that I could die by grounding myself with the hot terminal of an electrical outlet?I understand that the average current flowing through me is the product of RMS-voltage over resistancebut this value doesn't seem NEARLY high enough to do any damage much less for me to detect.Thanks!

okorder

Q:I payed the bill and put in the shutoff notice for the 18th, not the 16th! Jesus Christ! I still have shite I have to move!

Look at the money you're saving. 0_o

Q:I measured it with a CRO in the physics lab and I was wondering what could be its source

That is a period of about 62 hours or 2.5 days! Are you sure you measured this with an oscilloscope, or does CRO mean something else to you? Maybe the motion of the planets, earth, moon, etc. I don't know? Do you mean a period of 4.5 microseconds? That would be 222kHz perhaps EMI from a computer, other electronic gear, short wave radio, etc. If you can clarify, I might be of more help. Edit: OK; I have a couple of ideas, but it can be DIFFICULT to find. I spent a long time trying to track down the source of 70MHz in my lab. Turns out there is a TV station (channel 4) transmitting about 1 mile away. Channel 4 occupies the space between 67.31MHz and 71.75MHz. 222 KHz has a wavelength of about 1350 meters. It takes a pretty big antenna to launch that as a traveling wave so I'm going guess its a near field source. A good way to look for it is to make a small loop antenna with a few turns of magnet wire (maybe a few 10s of cm in diameter) and hook it to your oscilloscope. Walk around with it putting it near any and all electrical equipment that is in or near your lab. Make sure to change the orientation of the coil when you are moving around. You are basically playing a game of hot and cold. Try to maximize the signal and in theory you should be near the source. Also, be suspicious of the lights. I know their source is 60Hz, but some electronic ballasts for fluorescents run at a pretty high frequency, at least 10's of KHz, you could be seeing a harmonic. Just try flipping the lights on and off looking for a change in amplitude of the signal on the scope. If this doesn't find it, then perhps it is far field? I don't know of any commercial braoadcasts at this frequency though. The low end of AM radio is around 500KHz. Maybe you have an active Ham radio operator in the neighborhood? I wouldn't think he would be transmitting all of the time though is this 'noise' always present? Hope this helps. Let me know if you find it. Dave

Q:Before anyone blindly answers this, I'd like to first request that only people in the power transmission industry answer, as they are the only ones likely to know.I have a customer who is asking to mount several very large pieces of electrical equipment 15 feet in the air, mounted to a large structure. All of these equipment pieces are 5000 or more pounds and pad-mount by design. I am questioning this request on the basis of legality. Basically, I am curious to know, is there anything in the NEC that says mounting pad-mount equipment overhead is illegal? If so, I could really use a hint as to what section of the NEC code.

I don't believe that there is anything in the NEC that addresses this. Obviously, installing anything on a structure presents challenges that require the attention of a qualified structural engineer. And depending on the location, you could be facing some additional concerns. You would need to check on seismic activity in the area, and since 'pad mount' equipment has a broad profile, wind-loading could be more challenging if you have a wind-force specification to meet. The other issue you would need to consider is whether installation on a structure presents any particular safety concerns. Without knowing any more, my inclination would be to think that you might want to provide an enclosure around the structure to prevent civilians (rmeaning 'teenagers and drunk college students) from climbing it. Just out of curiosity - why does your client want this? We know that the client is always right - even when he insists to stupid things. I trust there is a good reason for asking for something that is bound to increase installation cost by probably 100%.

Q:2)Please do include the details as to why does spark devlop wn connection at one end is loose. 3)How the +ve electrode retains itz polarity though it accepts the electrons continuously, in a closed circuit.

1) For laymen understanding, electrical grounding is a protection of your house against lightning, instead burning your house or someone inside your house gets fried. In your appliances, electrical grounding protects you from getting electrical shock in case one of the electrical wire touches the metal body of your appliance. Now on electronic grounding, it is a protection of a certain circuitry from getting damaged by an electrical charge from your body in case you touch it. 2) Electrical wire connection is like a water pipe connection. Electrical current passes through the wire while water current passes through the pipes. If there is a loose connection of a certain electrical wire, or loose pipe connections on your water pipes; The loose pipe connections will produce leaks while the loose electrical connections will produce sparks. 3) It always retain its polarity always. Just like magnets, it retains its polarity, north and south. Electricity is based on magnetism. Law of nature.

Q:If this is maintained, but voltage changed from 480V to 240V, by what ratio will supply line losses change?

Power voltage x current Therefore current power/voltage. Thus, if power is constant at 2000kW current at 480 volts will be: I 2000,000/480 4166.67amps At 240 volts: I 2000,000/240 8333.33 amps However, line losses are current (squared) x resistance Thus the ratio will be 4166.67 (squared) / 8333.33 (squared), resistance remaining constant of course. I make that 0.25 (or 4, if you are thinking that way up!) That help?

Q:Electrical system in a residential building. When we use any equipment on one phase the lights on that phase dim down but and the same time the lights on the second phase become brighter.

the neutral of the building is disconnected from the utility mains neutral, that's why you are getting different voltages for different loads call a good electrician to reconnect the neutral And this problem can only happen when the building is connected with a 3 phase electric supply

Q:If I bring my laptop (North America 60Hz) and use it in Europe (50Hz), would it work properly?If so, does that mean my laptop/power cord has a frequency converter?

my laptop has an internal battery, so it can operate with no outside voltage at all. The power adaptor is rated 100-240 volts 50/60 cycle input with no adjustments needed. such ratings are very common for this type of equipment. what will be needed is converters for the blade type plug to the kind in use for the country you are visiting. If you are going to be in Europe for an extended period, you should be able to get the proper line cord for the power adaptor from the computer manufacterer.

Q:every electrical equipment is rated in VA or KW(motor) why transmission line rated in Volts though it carry power.

Because voltage is the only thing that remains fairly constant. Even though industry and residential pull off that transmission line, the voltage is and Hertz is maintained for the sake of equipment that depends on a constant voltage. The current in the line fluctuates highly , depending on how many people are drawing on it at any instant

Q:I think that management hired a secrets spy to test me and quiz me just to make sures im doing my jobbed properly, ok? They have been hiding behinds the bushed by the water coolers with binocs and clipped boards and i think they are jottings down secret spying informations on me. I also think they planet a bugs on my desk arena and are secretly recordings and monitorings my every moved, ok? How do I find the bugs and are they recordings me right now? am i being monitaried? I already searched all of the potted plants and drawers in my desks and several other coworkers desks in my arena, ok? I am very scared of bugs and of the peoples watching me in the bushed, ok? I am very worrieds that they are monitaring me right now because i talk alouds when i types into my new headphoned typing deviced set, ok? maybe the bug is in there? ok? how do i get it outs if i am not electronical? will it permenentaly ruin my headphoned? ok?

They are looking at you, ok. and they've put software on your computer which monitors which web sites you go to, ok. They're monitoring your productivity by the number of keystrokes you type, ok. They're also monitoring your phone and even have a camera so they can record your eye movements on your computer screen, ok. They've put cameras in your plants, in your desk, in your filing cabinet and your headset so they can see EVERYTHING you're doing, ok. They're in the closets, the breakroom and the lunchroom, ok. They're in your headphones, ok. They've even planted a small camera just inside your urethra so they can tell if you're taking too many bathroom breaks and so they can see just exactly what you're doing when you're inside the bathroom stall, ok. You're screwed, ok.