Electric charge là gì

     
Tĩnh điện là gì

Tĩnh điện là hiện tượng lạ mất cân bằng điện tích trên bề mặt của một trang bị liệu. Điện tích sẽ tiến hành lưu giữ ở đó cho đến khi nó rất có thể truyền đi vị trí khác thông sang 1 dòng năng lượng điện hoặc sự phóng điện.Bạn đã xem: Electric charge là gì

Static is generated when two objects made of different electrically neutral materials liên hệ and then separate.Bạn vẫn xem: Electric charge là gì


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1) contact between objects A và B

Electrically neutral objects A & B (with equal quantities of positive and negative charges)

2) Transfer of charge

When metals contact each other, electrons move from one with a smaller work function khổng lồ one with a larger work function. In other words, metal with a smaller work function will be charged positively and one with a larger work function negatively.Bạn vẫn xem: Electric charge là gì

3) Separation between objects A & B

Object A is charged negatively và object B positively.

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Figure 1. Static generation due to liên hệ charging

Static is generated when two objects tương tác and then separate. The combination of the two objects may be solid and solid, solid và liquid, or liquid và liquid. Figure 2 shows examples.


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Figure 2. Examples of static generation

All the above phenomena involve liên hệ between two objects and their separation.


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Figure 3. Examples of charging

Friction between two objects in a triboelectric series causes the object in the upper position of the series to be charged positively & that in the lower position to lớn be charged negatively. Friction between two objects positioned far apart (C) also generates a larger amount of static than ones closer khổng lồ each other (B) and much closer to each other (A) (A

When an object is charged

When an object is charged electrostatically, an electrical field is generated around the charged object, as illustrated in Figure 4.

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Figure 4. Electrical field generated around charged objects

Starts from a positive electric charge và ends in a negative electric chargeLines vày not intersect each otherDoes not branch offThe electrical field is strong when lines of electric force are denseThe electrical field is uniform when lines of electric force are parallelComes out of (enters into) the surface of a conductor vertically


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(a) Lines of electric force between objects with different electrical polarities

(b) Lines of electric force between objects with the same electrical polarity

Figure 5. Lines of electric force formed between two charged objects

E1: Strength of electrical field on a conductor surface

Density of lines of electric force: Low à Electrical field is weak

Charged conductive sphere A

E2: Strength of electrical field on a conductor surface

Density of lines of electric force: High à Electrical field is strong

Charged conductive sphere B

Figure 6. Lines of electric force from two charged conductors with different quantities of electric charge

What is electrostatic force (Coulomb force)?

Electrostatic force (Coulomb force) is the source of an electrostatic phenomenon. As Figure 7 shows, the direction of the force between two charged objects differs according lớn whether the objects have different electrical polarities or the same electrical polarity. Electrostatic force is an attractive force (a) when the polarities are different and a repulsive force (b) when the two objects have the same electrical polarity.

(a) Force between objects with different electrical polarities

(b) Force between objects with the same electrical polarity

Figure 7. Electrostatic force between two charged objects

As Formula (1) shows, the strength of the electrostatic force (Coulomb force) is proportional to lớn the product of the quantities of the electric charge of the two charged objects & inversely proportional to lớn the square of the distance between the two objects.

F ∝Q1・Q2/r2 ・・・・・・・・・・・・(1)

Electrostatic induction is also caused by electrostatic force

Figure 8. Electrostatic induction caused by electrostatic force

Electrostatic discharge is also caused by electrostatic force (Coulomb force)

Figure 9. Generation of electrostatic discharge caused by electrostatic force

The electrical field around the charged object causes the negative ions (electrons) therein to lớn be accelerated by the electrostatic force (Coulomb force), thereby having kinetic energy (wv). When these negative ions strike gas molecules in the electrical field và the following formula is true,

Ionization energy of the gas molecules

electrons are sputtered from the gas molecules, resulting in generation of negative ions và positive ions. The gas molecules are ionized if the negative ions thus generated are subject to action of the electrostatic force & the negative ions are accelerated in the electrical field with its kinetic energy meeting the condition expressed in formula (2) above. Repetition of this process results in generation of electrostatic discharge.

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Charge distribution of a conductor is also influenced by electrostatic force (Coulomb force)

Figure 10. Distribution of electric charges on a charged conductive sphere

(a) Conductor with surface potential distribution

(b) Electric charges that are distributed in a way that makes the conductor surface equipotential

Figure 11. Electric charges are distributed on a conductor surface in a way that makes the surface equipotential.