Application of Electrostatic Phenomena in High School Physics, Application of Electrostatic Phenomen

High school physics, applied knowledge of electrostatic phenomena.

1 Electrostatic equilibrium.

The state in which the free electrons in the conductor no longer move in a directional manner is called the electrostatic equilibrium state

2 Electrostatic balance characteristics.

1) A conductor in electrostatic equilibrium with zero internal electric field strength;

2) The whole conductor in electrostatic equilibrium is an equipotential body, and its surface is an equipotential surface

3 Charge distribution characteristics of electrostatically balanced conductors.

1) The inner and outer surfaces are differently distributed, the charges are distributed on the outer surface, and there is no charge inside the conductor

2) Affected by the shape of the conductor, the charge density is high in the non-smooth area On the surface of the conductor, the sharper the position, the greater the density of the charge, and the concave position has almost no charge

3) The "far and near" charges are opposite in their electrical properties and have equal charges

As shown in the diagram, when two or more conductors that were originally insulated from each other are contacted or connected by wires, they can be regarded as one large conductor, and the "contact of a conductor by hand" mentioned in some questions is actually the conductor forming a large conductor through the human body and the earth

4 Tip discharge.

1) Ionization phenomenon: the phenomenon of separation of positive and negative charges in the molecules of gas molecules in the air under the high-speed impact of charged particles

2) Tip discharge: The charge at the tip of the conductor attracts the charge in the air that is opposite to its symbol, and the charge on the tip is neutralized and loses its charge, a phenomenon called tip discharge

5 Electrostatic shielding.

A cavity conductor in an electric field has no electric field in the cavity because there is no electric charge on the inner surface, and this phenomenon is called electrostatic shielding

There are two cases of electrostatic shielding:

1) The external electric field of the conductor does not affect the inside of the conductor, that is, the superposition of the external electric field and the induced charge on the surface of the conductor at any point in the conductor is zero

2) The internal electric field of the grounded conductor does not affect the outside of the conductor because the induced charge outside the conductor is repelled into the ground, so that the superposition of the induced charge and the induced dissimilar charge on the inner wall at any point of the electric field strength outside the conductor is zero

The answer is to choose C No, after the outer wall contact, E has a positive charge and contacts on the inner wall of A. 1. The charged body is electrified, because it is the same kind of charge, so it repels each other, and is finally distributed on the surface of the charged body and is in a stable state. 2. After 1 contact with A, similarly, A is charged on the outer wall, so the contact on the inner wall, because the same charge is in contact, what is obtained is only the mutual transfer between the same charge, and the transfer amount of charge depends on the amount of band point of the conductor carrying the charge and the external geometry.

3. When E is in contact with A, the positive charge is in the inner wall of A, and then transferred to the outer wall of A, so the amount of charge on the inner wall is always zero at this time, and the inner wall of A is always free of charge. 4, so in the process of transfer, the inner wall of A in the two charged bodies, which is always zero, can obtain the maximum charge transfer. To sum up, choose C

I really can't see the picture of the landlord, but to solve this problem, the high school celebration and stage can basically solve the defeat with the equivalent method.

1 Electrostatic induction is nothing more than the side close to the charge induces a different species, and the side away from the charge induces the same species.

2 The essence of the metal ball grounding is to become a whole with the earth, and the earth becomes the other end of the distance.

3 Do not think that the charge has entered the earth, but that the same charge is actually induced on the other side of the earth.

I hope you understand and can help you.

First of all, due to the phenomenon of electrostatic induction, the inner surface of the metal ball is positively charged, and the outer surface is negatively charged. After grounding, the charge in the earth is neutralized with the negative charge, and there is no reed on the inner surface.

That's the question, hehe, that's it.

First of all, it is clear that the conductor rod and the ground are insulated, so although there is an induced charge on the conductor rod before the finger touches, the net charge is 0, this is no problem, right?

Secondly, the hand touches it, no matter whether it touches **, it is to connect the conductor rod with the earth, so after touching, the contact part becomes the far ground end (the same is true for touching a), so after the hand touches it, the near ground end will induce a negative charge, and the far ground end has no charge because it is connected to the earth, and the net charge on the conductor rod is not 0, but negative.

After removing the hand, it is equivalent to insulating the conductor rod again, so the negative charge on the conductor rod has nowhere to go, and it will be distributed on the surface of the conductor rod, so the negative charge is a thing.

Do you understand?

The finger is one with the person. The fingers are in contact with the conductor rod AB, and the person stands on the earth, which forms a whole (AB + person + earth). Due to the proximity of the whole to q, the free electrons in the whole move to the end of the whole that is close to a positive charge (i.e., the conductor rod AB), resulting in the AB terminal being negatively charged.

The same is true for the two blanks, in fact, the questioner divided the two blanks in order to confuse the students.

After the conductor is close to the positively charged Q, the phenomenon of electrostatic induction will occur, the left end of AB, that is, A, will be negatively charged, because the original is not charged, so B will be positively charged, after touching B with your hand, the positive charge on B will move to the hand, after removing Q, AB will be charged depending on the A end, so it is a negative charge.

The same can be analyzed to get the second answer.

1.There is a positive charge on the outside of the grounded metal ball, and an induced charge will be generated on the surface of the metal ball, and the electric field of the induced charge is superimposed with the electric field of the positive charge outside the metal ball, so that the electric field inside the metal ball is zero. This is called electrostatic shielding.

2.Only the same amount of different charge can achieve electrostatic equilibrium. If the distance between the two changes, there should be an effect on the charge distribution of the latter, but no effect on the charge.

3.If there is a positive charge inside an ungrounded (hollow) metal ball, the electric field inside and outside the ball is the same as that of the non-metal ball, except for the metal ball part, and the whole space is an electric field formed by a point charge.

4.If there is a positive charge inside the grounded (hollow) metal ball, there is an electric field formed by the point charge inside the metal ball, and there is no electric field outside the metal ball because it has the same electric potential as the ground.

5.Whether it is in a hollow metal ball, a metal spherical shell, or an insulated metal shell, there is only a difference between grounding and non-grounding.

There is no difference, the metal has a shielding function, and if the charge is inside the metal, then the electric field outside the metal is the same.

Take your time, qualitative change must have the accumulation of quantitative change, think more, and be proficient to open your mind. The direction in which the electric potential decreases the fastest is to take an electric field line or a parallel electric field line in a uniform strong electric field, while the electric field line of the positive and negative point charges is divergent and points to all directions in all directions, that is, the direction of the electric potential decrease is an infinite number of directions in all directions. And an electric field line can only point in one direction, and there are countless directions in which the electric potential decreases equally fast, so the second half of the sentence is wrong.

Because there is only one direction in which the electric potential of a uniform electric field decreases the fastest, the first half of the sentence is correct.

When the metal rod and hand are connected as a whole, the electricity flows to the earth, so it is undetectable. It is possible to have insulated gloves to hold the metal rod.

1.According to the force analysis, the e=mg (tan a q )2The work done by the electric field force and gravity is w=-1 2 mv*2=-(w(gravitational force)+w(electric field force))=mgh+uq).

mgh+esq）

where U is the potential difference, S is the maximum horizontal displacement, and H is the vertical maximum displacement.

And tan a = h s so, if s can be found and u=es gives u=......I'm sorry, I don't have to wait for it, I just provide ideas)

In a conductor that achieves "electrostatic equilibrium", the internal field strength of the conductor is zero, and the charge is only distributed on the outer surface of the conductor, and the sharper the point, the greater the charge density.

The function of the wire here is to make the ball and the spherical shell become a whole, so the ball is equivalent to the outer surface of the conductor when it is outside the spherical shell, so it is positively charged.

There are many applications of electrostatic phenomena in life, electrostatic copying, is the use of static electricity to adsorb toner on the drum Electrostatic precipitator is the use of static electricity to attract light and small objects Electrostatic spraying is the use of spray guns to spray paint particles are positively charged, due to mutual repulsion and scattering, forming a fog, the sprayed object is negatively charged, the fog paint has a gravitational force, and the paint is sucked to the surface

So the answer is: electrostatic copying; Electrostatic spraying

1. Electrostatic precipitator.

2. Electrostatic printing, such as photocopying, spraying and spraying, etc.