An isolated charge, around an isolated stationary point charge

There is an electric potential difference in the presence of an electric field, so there is an electric potential difference between an isolated charge and the earth;

So there is an electric current;

The medium between the earth and the point where the isolated charge is located can be regarded as a capacitance, and when a person touches this charge, it is equivalent to connecting the two ends of the capacitor, which is the discharge circuit;

Whether static electricity generated by friction can be felt depends on the potential difference between the human body and the object in contact. If there is a potential difference and the object in contact is also conductive, there will be an electric current, such as shaking hands with people, touching metal objects, and so on. You can't feel it when you come into contact with insulators, such as the handle with a plastic sleeve on the bus, and your own clothes.

Yes The earth itself is negatively charged, the total charge is very large, but it is dispersed, there is an electric field around the earth, and the charged person in this electric field will be affected by it, and we generally think that the electric potential is 0 at infinity from the earth, and the electric potential is getting lower and lower along the direction of the electric field lines around the earth (electrically for the study of virtual lines, you should know) So it can be known that even if there is an electric potential difference between an isolated charge and the earth, as for the second question, theoretically, yes, if the charge charge is large enough, it can be felt Any two objects of different materials will be transferred and accumulated when they come into contact, forming static electricity. Static electricity on the human body is mainly caused by the friction between clothes or between clothes and the body, so when wearing clothes of different materials, the "electricity" is more or less different, for example, wearing clothes made of chemical fibers is more likely to produce static electricity, while cotton clothes produce less. And because the dry environment is more conducive to the transfer and accumulation of electric charge, people will feel that the static electricity on their bodies is greater in winter.

Hehe, the static electricity generated by friction will not be very large and long-lasting so.

Answer] :d hint that the stationary charge produces an electric field that does not produce a magnetic field, and the electric field is an active field that points from a positive charge to a negative charge.

<>1) Electric field lines with isolated negative charges.

From infinity to the end of the negative charge, the distribution of the electric field lines is shown in the figure on the left 2) The electric field lines of the same amount of dissimilar charge are always open from the positive charge.

The distribution of its electric field lines from the departure to the termination of the negative charge is shown in the figure on the right

There may be an electric charge inside, but the electric field is zero. So that the external charge does not move. There is some knowledge that cannot be understood at a certain stage, and it can be regarded as a kind of regulation.

Because electrons can move freely, if they are not zero, electrons must move under the action of the electric field until an additional electric field is generated to cancel out the original electric field, and the electrons no longer move, reaching electrostatic equilibrium. So the internal electric field must be zero under electrostatic equilibrium.

Since the isolated conductor also has a large number of free charges, these free charges will want to move in opposite directions under the action of the external electric field, forming charge separation, and these free charges with opposite charges will also form an electric field opposite to the original electric field. If the electric field in the problem has not been canceled out, the free charge will continue to move under the action of the electric field, and further cancel out the field strength of the external electric field until the electric field inside the conductor is 0 everywhere, which is the principle of electrostatic equilibrium. Electrostatic equilibrium is mainly the concept that the electric field generated by the separated free charge cancels out the original external electric field, not that the field strength generated by the charge cancels each other out.

If it is a sphere of metal, ideally, the charges are all concentrated on the surface and evenly distributed.

Let a positive charge q be moved from point A to infinity, then there is: wa qua due to the electric field force doing negative work on the positive trapped trembling charge, i.e., wa 0, q 0 so ua

And because of Wang Min ua a

a, so a0, get the proof of the hole.