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How does my Ikea lamp work?

monkeybanana

Jan 21, 2012
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Jan 21, 2012
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Hello everyone,

This is a little random but here's the deal: I love thinking about power transmission and while I was sitting on my sofa looking up information about my power outlet I noticed and started to admire my little Ikea Espressivo lamp. I was hoping some of you could help me understand physics a little more.

So what I notice in the base is that there is only a transformer. Two wires connect to the telescoping stands which is are not insulated and at the other end two wires connect to the bulb. Here are my main questions:

Why is it that when I touch both of the stands I do not get electrocuted? I put some probes right on both stands and got about 11.5 Vrms. The current reading is real low: about 40 micro amps I think. Of course I'm trying to measure AC. Regardless, I thought that decreasing the voltage should increase current. So does that mean that the halogen bulb has a high resistance to protect from shock?

I have enclosed some pictures. They are not the best but hopefully you can see what I am trying to describe.

Thanks!

edit: Is there a way I can edit my typo in the title? I don't have a lam but a lamp
 

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Last edited:

BobK

Jan 5, 2010
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11.5V will not electrocute you.

You cannot measure the current by clipping onto the two leads. You have to break one of them and put the meter in series with it. I am sure you would read 1 or more amps that way.

Bob
 

monkeybanana

Jan 21, 2012
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Jan 21, 2012
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11.5V will not electrocute you.

You cannot measure the current by clipping onto the two leads. You have to break one of them and put the meter in series with it. I am sure you would read 1 or more amps that way.

Bob

You're right. I should have known that bc that's some basic electronics stuff. I was also trying to see if I could put something in parallel with the bulb and do something with the lamp for fun.

I would expect maybe some shock from this set up though
 
Last edited:

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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I would expect that there is something there which limits the current. I suspect the transformer is designed in such a way that a short will not cause it to lose its smoke (how else could you place the supply rails on uninsulated exposed metal?)

Certainly seems to be designed to a price point...
 
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