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If I have walked on a carpet with my shoes, and then go near the knob of a door, the excess electrons in my body get discharged to the knob.

  1. Are all the excess electrons transferred to the knob?

  2. What happens to the excess electrons that got transferred to the door knob? Will the knob stay negative, and the carpet stays positive, forever?

  3. Since the human body is also a conductor just like the knob, why would a transfer of electrons take place to the knob?

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  1. Usually the door knob is connected to earth by a wooden door (and other materials of the building). Wood is a conductor for static electricity. When your hand touches the door knob for a second or so, all the excess electrons will flow from your body to earth.
  2. The discharge time for the excess charge is less than a second, as can be easily observed with an electroscope, when touching the knob. All excess charge leaks away to earth.
  3. The transfer of electrons to the knob usually takes place because the knob is connected to earth. If, however, the door is made of an insulator like glass, there is no path to earth, so only some fraction of the excess charge would flow from the body to the knob. That fraction is $\frac{C_k}{C_k+C_b}$.

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