I Question about the current through a strong insulator

AI Thread Summary
When a strong insulator is placed underfoot and a test light is connected to an electrical outlet, the light can still illuminate due to the small alternating current (AC) that flows through the capacitance between the body and the ground. This current, although minimal, is sufficient to activate the test light. The discussion highlights that even a thick insulator can allow current to pass through its dirty or hygroscopic surfaces, creating a path to ground. Calculations indicate that a body capacitance of 100 pF at 230 Vrms can produce an average current of approximately 6.5 µA, enough to light the test device. The inquiry about the nature of the test light suggests a need for clarification on whether it is an isolated AC Mains Safety Detection Device.
abdossamad2003
Messages
68
Reaction score
4
Suppose we put a strong insulator under our feet. In this case, when we connect the test light to the electrical outlet, the light of the test light lights turn on. I wonder how the electric current can pass through the strong insulator. If we calculate, the electric current cannot be more than 10^-18 amp which cannot turn on the test light lamp in any way.
 
Physics news on Phys.org
abdossamad2003 said:
I wonder how the electric current can pass through the strong insulator.
The current that flows is AC at the mains frequency. The small current needed to light the test light passes through the capacitance between your body and the nearby ground.

A thick sheet of good insulator will also conduct current across the hygroscopic dirty surface and around the edges of the sheet to ground.

Edit; Do the numbers.
Assume a minimum of 100 pF of body capacitance, 50 Hz, 230 Vrms.
Vpp = 2.8 * 230 = 650 volts slew in about 10 ms.
C = q/v = i·t/v ; i·t = c·v ; i = c·v/t
Average current; 100e-12 * 650 / 0.01 = 6.5 uA
 
Last edited:
  • Like
Likes DaveE and Delta2
abdossamad2003 said:
Suppose we put a strong insulator under our feet. In this case, when we connect the test light to the electrical outlet, the light of the test light lights turn on.
I'm confused by your question and situation. By "test light", do you mean an isolated AC Mains Safety Detection Device? If so, the answer given by @Baluncore is correct.

1705426252567.png

https://www.walmart.com/ip/Fluke-FLK2AC-90-1000V-90-1000-VAC-Detector/102480670
 
Thread 'Motional EMF in Faraday disc, co-rotating magnet axial mean flux'
So here is the motional EMF formula. Now I understand the standard Faraday paradox that an axis symmetric field source (like a speaker motor ring magnet) has a magnetic field that is frame invariant under rotation around axis of symmetry. The field is static whether you rotate the magnet or not. So far so good. What puzzles me is this , there is a term average magnetic flux or "azimuthal mean" , this term describes the average magnetic field through the area swept by the rotating Faraday...
Back
Top