# How can there be a path to ground with thick shoes and a carpet?

I'm connecting a test light to one pin of an halogen lamp. When I touch the metallic part on the back of the test light, the light glows, as it is supposed to. However, I have thick shoes and I am standing on a carpet. How could I possibly provide a path to ground?

I have tried:

• to stand on a plastic sheet -- the light still glows with the same intensity
• to touch a radiator with the other hand -- the light is much more intense
• to interpose my shoe between the metallic part of the test light and me -- the light does not glow
• to interpose a paper sheet -- the light still glows

Thank you for any response

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I'm not sure (hence a comment rather than an answer) but I think the path to ground is through the air. Your body provides a large surface area, making it easier for charge carriers (electrons? Ions? I don't know) to pass through the air to the conductive objects in the room. – Nathaniel Jan 22 '12 at 12:02
Perhaps you could test this hypothesis by attaching a large piece of tin foil to the contact instead of your body... – Nathaniel Jan 22 '12 at 12:03
My guess is that you form part of a capacitor that would saturate after a while. Have you tried long enough to see if the light diminishes after a while? – anna v Jan 22 '12 at 12:25
@Nathaniel I tried what you suggested and it worked, so thanks for your suggestion – Fiat Lux Jan 22 '12 at 12:52
@annav I think you would be right if my source were a DC supply, but it is alternated current, so I believe twistor59 is right – Fiat Lux Jan 22 '12 at 12:53

If the effective area for you-air-ground is 1$m^2$ say, and the testlightpin-shoe-you is 1$mm^2$ say, then (ignoring the dielectric properties), the ratio of the capacitances is 1:1000000. Now the series capacitance is totally dominated by the smaller one (1/C = 1/C1+1/C2), which is the testlight-pin-you one by a factor of a million. (Goodness knows how accurate the estimates are, but you get the general idea !) – twistor59 Jan 22 '12 at 15:02