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Juice
Jul 11, 2005 8:07:53 GMT
Post by compsci on Jul 11, 2005 8:07:53 GMT
Since the cane was abolished and teachers lost the ability to get revenge by beating the little darlings, they've had to resort to more covert means. The usual method used by the science department in my old school involves showing the class an AA battery, and getting them to agree that they couldn't possibly get an electric shock from it. Then get the children you hold a grudge against to form a circle, holding hands, produce a capacitor to go with the battery and ZAP!  (Van de Graaf generators can also be used, and deliver more of a jolt, but they tend to arouse more suspicion) |
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Phil
In memoriam
RIP 23-Oct-2018
Posts: 9,473
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Juice
Jul 11, 2005 13:51:40 GMT
Post by Phil on Jul 11, 2005 13:51:40 GMT
I remember in a science lesson once my teacher got electrocuted. I was kind of day dreaming and heard this "Oh brown stuff" come from the front of the classroom and saw him be thrown back. It should be funny be it is! (ROFLMAO as I type). I don't know about the voltage, but it wasn't small! All school lab. supplies are required to be no more than 115volts to earth despite what the socket looks like. The minimum lethal voltage for a normal human body is about 120V........ |
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Juice
Jul 12, 2005 11:07:56 GMT
Post by Dmitri on Jul 12, 2005 11:07:56 GMT
60V in a PHONE LINE  Russian standard (with current limited to about 30-40 mA on the phone station - can't recall exact value of the resistor). Ring voltage - normally up to 120 V, may be even more for long-distance calls. I think a transformer and a rectifier is enough  . Never happened to me, and I've spent a considerable amount of time dealing with car batteries and 12 V rectifiers. |
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Juice
Jul 12, 2005 11:14:16 GMT
Post by q8 on Jul 12, 2005 11:14:16 GMT
12v may not sound much but can (and does) give you a bloody nasty belt.
Never happened to me, and I've spent a considerable amount of time dealing with car batteries and 12 V rectifiers.
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You must be made of rubber then 'cos the last time I accidentally bridged some car battery terminals I'm bloody sure my b*lls went CLAAANNNGGG!!
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Juice
Jul 12, 2005 11:57:33 GMT
Post by Hutch on Jul 12, 2005 11:57:33 GMT
All school lab. supplies are required to be no more than 115volts to earth despite what the socket looks like.
The minimum lethal voltage for a normal human body is about 120V........ The continuing number of accidental household electricutions in North America attest to the lethallity of 120V. It's the current that kills and milliamps will do the trick. Ohm's Law applies. The 110V supplies on a British building site (and maybe those refered to in the classroom) are centre tapped in that both current carrying pins are 55V to ground, 180 deg out of phase with each other. That voltage is on par with a telephone line and hence the great reduction in building site electrical accidents. The person who thinks that a 12V driven car electrical system cannot bite has obviously not got between the naughty end of the coil and the plugs. I think that at the moment of "OOuch!!!", the potential is in the range of several thousand volts.  |
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Juice
Jul 12, 2005 15:33:47 GMT
Post by Dmitri on Jul 12, 2005 15:33:47 GMT
The continuing number of accidental household electricutions in North America attest to the lethallity of 120V. It's the current that kills and milliamps will do the trick. Ohm's Law applies. In an attempt to disillusion those who thinks that they've finally started to understand something, I'd remind that human body from the electrical standpoint isn't as simple as resistor: the only body part with relatively high resistance is the thin outer layer of skin. If the externally applied voltage is higher than breakdown voltage of the skin, there is almost nothing to limit current. More likely, something else instead of "OOuch" would be heard  , as ignition voltage can be even higher than 10 kV. One of the nasty tricks is to take 220->5...12 V transformer, give 220 V winding to someone unsuspecting, connect an AA battery to the lower voltage winding... then disconnect the battery and watch him jump . The principle is the same as of car ignition. However that may be, I'm used to take electricity seriously - the 220 volts in the home wall outlet makes a food for thought ;D. |
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Juice
Jul 12, 2005 18:10:01 GMT
Post by yellowsignal on Jul 12, 2005 18:10:01 GMT
the only body part with relatively high resistance is the thin outer layer of skin. If the externally applied voltage is higher than breakdown voltage of the skin, there is almost nothing to limit current. Something Saddams special police and their 'suspects'were extremely aware of. |
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towerman
My status is now now widower
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Juice
Jul 15, 2005 20:01:41 GMT
Post by towerman on Jul 15, 2005 20:01:41 GMT
One thing that will stay with me till my dying day is the smell of burning flesh
after someone is "juiced up" just like somebody's peed on a bonfire.We had a chap get into Hainault one night,before all the fences and CCTV,he walked down from Grange Hill to just past the North Shunter's Cabin then took off all his clothes and then went to sleep across the posi and running rail,needless to say it was the last thing he ever did!!He wasn't found till 06:00 the next morning and you could smell it as soon as you left the shed.We weren't allowed to move him till a doctor arrived and pronounced him dead.the best of it was when the shunters went to move the train on 61rd that had been cancelled due to the incident they found his mate fast asleep across the seats,pity the other fella couldn't have done that.
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Deleted
Deleted Member
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Juice
Jul 15, 2005 20:34:08 GMT
Post by Deleted on Jul 15, 2005 20:34:08 GMT
I once got a belt from jumpimg 24v from 4x6v bus batteries straight to the starter motor, which AFAIK, draws around 300amps. Not fun when you are laying under said bus with not much room to move. Sudden movement + confined space + exhaust silencer = pain ;D My mate who worked for BR showed me an extract from the control log about a bloke who went for a p*ss off an overbridge near Penrith. Ouch  |
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Juice
Jul 20, 2005 12:09:58 GMT
Post by Nick Booth on Jul 20, 2005 12:09:58 GMT
The dampness is no factor, the fluid inside the body is. Humans consist of 95% water (as do foxes i suppose), water turns to steam and that can make a cadaver explode if heated rapidly enough. The same thing happens to trees when lightning strikes, the tree explodes because sap is heated and turns into steam. And, as I recall, to pigeons sitting on the live wire at York when they raised their wings to take off. The passengers (sorry, customers) on the platforms did not take kindly to being spattered by exploding pigeon.... |
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Juice
Jul 20, 2005 12:46:53 GMT
Post by compsci on Jul 20, 2005 12:46:53 GMT
I've just remembered my Dad mentioning that the Metro service in Newcastle was once suspended briefly after a child let go of their Mr Blobby helium balloon.
The balloon floated up into the tunnel roof and encountered the overhead wires. This caused the balloon to explode, and tripped the breakers at the substation (presumably it shorted out the wires and their supports or something).
I don't think anyone was injured, as the string on the balloon wasn't long enough, but I imagine the passengers were rather alarmed.
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, as ignition voltage can be even higher than 10 kV. One of the nasty tricks is to take 220->5...12 V transformer, give 220 V winding to someone unsuspecting, connect an AA battery to the lower voltage winding... then disconnect the battery and watch him jump 
