Presentation on the topic of dielectrics. Presentation on the topic "conductors and dielectrics." The dielectric weakens the external electric field

04.03.2022 Kinds

1. In the absence of an external field, particles are distributed inside the substance in such a way that the electric field they create is zero. 2. In the presence of an external field, a redistribution of charged particles occurs, and a substance’s own electric field arises, which consists of the external E0 field and the internal E/ created by the charged particles of the substance? What substances are called conductors?

3. Conductors -

substances with the presence of free charges that participate in thermal movement and can move throughout the entire volume of the conductor 4. In the absence of an external field in the conductor, the “-” free charge is compensated by the “+” charge of the ionic lattice. In an electric field, occurs redistribution free charges
, as a result of which uncompensated “+” and “-” charges appear on its surface This process is called electrostatic induction , and the charges that appear on the surface of the conductor are.

induction charges 5. The total electrostatic field inside the conductor is equal to zero 6. All internal areas of a conductor introduced into an electric field remain electrically neutral 7. This is the basis electrostatic protection – devices sensitive to the electric field are placed in metal boxes to eliminate the influence of the field.? What substances are called dielectrics? 8. In dielectrics (insulators) there are no free electric charges

. They consist of neutral atoms or molecules. Charged particles in a neutral atom are bound to each other and cannot move under the influence of

electric field throughout the entire volume of the dielectric. 8. There are no free electric charges in dielectrics (insulators). They consist of neutral atoms or molecules. Charged particles in a neutral atom are bound to each other and cannot move under the influence of an electric field throughout the entire volume of the dielectric. 10. Bound charges create an electric field that inside the dielectric is directed opposite to the vector of the external field strength. This process is called dielectric polarization. 11. A physical quantity equal to the ratio of the modulus of the external electric field strength in a vacuum to the modulus of the total field strength in a homogeneous dielectric is called dielectric constant substances. ε =E0/E

12. Polar dielectrics - consisting of molecules in which the centers of distribution of “+” and “-” charges do not match. 13. Molecules are microscopic electric dipoles - a neutral combination of two charges, equal in magnitude and opposite in sign, located at some distance from each other.

14. Examples of polar dielectrics:
Water, alcohol,

nitric oxide (4) 15. When a dielectric is introduced into an external field, a partial orientation of the dipoles occurs. As a result, uncompensated bound charges appear on the surface of the dielectric, creating a field directed towards the external field. 16. Non-polar dielectrics – substances in the molecules of which the centers of distribution of “+” and “-” charges match up.

17. Uncompensated bound charges appear on the surface of the dielectric, creating their own field E/ directed towards the external field E0

Polarization of a non-polar dielectric 18. Examples of non-polar dielectrics:

inert gases, oxygen, hydrogen, benzene, polyethylene.
1. What is the electric field inside the conductor?
A) Potential energy of charges

B) Kinetic energy of charges

B) zero
A) These are substances in which charged particles cannot move under the influence of an electric field.

A) These are substances in which charged particles cannot move under the influence of an electric field.

B) These are substances in which charged particles can move under the influence of an electric field.
A) 1 4. What is called polarization?
A) This is a displacement of positive and negative bound charges of the dielectric in opposite directions

B) This is a displacement of positive and negative bound charges of the dielectric in one direction

B) This is the arrangement of positive and negative charges of the dielectric in the middle
5. Where is the static charge of the conductor concentrated?

A) inside the conductor

8. Non-polar dielectrics are dielectrics in which the centers of distribution of positive and negative charges...

A) The fact that the electric field inside the conductor is maximum.

A) The fact that the electric field inside the conductor is maximum.
B) on the fact that there is no electric field inside the conductor

10. What is a dipole?

A) This is a positively charged system of charges
B) This is a negatively charged system of charges
B) This is a neutral system of charges

Slide 1

Conductors are substances in which there are many free charged particles. For example, in metals these are the electrons of the outer shell, which are connected with the nuclei of atoms very weakly and therefore actually belong to the metal conductor as a whole. This is the so-called electron gas. It is precisely due to the presence of charged particles that can move freely throughout the entire volume of a metal conductor that there is no electric field inside metals. There is no electric field in other conductors either. Consider the electric field inside a metal conductor......

Slide 2

Slide 3

Because E0 = E1, then E = E0-E1= 0 There is no electric field inside the conductor

Slide 4

When charges are in equilibrium, there is no electric field inside the conductor, and the charges are located on its surface.

Slide 5

Dielectrics

These are substances that have no free charged particles inside them. It is necessary to distinguish between polar dielectrics, in which the center of the positive and negative charge does not coincide. In non-polar dielectrics, the center of the positive and negative charge coincides. In an electric field, any dielectric becomes polar.

Slide 6

Dipole

This is a system of two connected opposite charges, in which the center of the positive and negative charge does not coincide. A dipole placed in an electric field is subject to a torque, causing it to orient itself along the field. M=F٠L, where L is the distance between the centers of bound charges.

On the surface of the sphere, cones cut out small spherical areas that can be considered flat. A r1r1 r2r2 S1S1 S2S2, or The cones are similar to each other, since the angles at the vertex are equal. From the similarity it follows that the areas of the bases are related as the squares of the distances from point A to the sites and, respectively. Thus,

Equipotential surfaces An approximate course of equipotential surfaces for a certain moment of cardiac excitation is shown in the figure. In an electric field, the surface of a conducting body of any shape is an equipotential surface. The dotted lines indicate equipotential surfaces, the numbers next to them indicate the potential value in millivolts.

Dielectric constant of substances Substance ε ε Gases and water vapor Nitrogen Hydrogen Air Vacuum Water vapor (at t=100 ºС) Helium Oxygen Carbon dioxide Liquids Liquid nitrogen (at t= –198.4 ºС) Gasoline Water Liquid hydrogen (at t= –252, 9 ºС) Liquid helium (at t= –269 ºC) Glycerin 1.0058 1.006 1.4 1.9–2.0 81 1.2 1.05 43 Liquid oxygen (at t= –192.4 ºС) Transformer oil Alcohol Ether Solids Diamond Waxed paper Dry wood Ice (at t= –10 ºС) Paraffin Rubber Mica Glass Titanium barium Porcelain Amber 1.5 2.2 26 4.3 5.7 2.2 2.2–3.7 70 1.9–2.2 3.0–6.0 5.7–7.2 6.0–10.4–6.8 2.8

Literature O. F. Kabardin “Physics. Reference materials". O. F. Kabardin “Physics. Reference materials". A. A. Pinsky “Physics. Tutorial for 10th grade schools and classes with in-depth study of physics." A. A. Pinsky “Physics. A textbook for 10th grade schools and classes with in-depth study of physics." G. Ya. Myakishev “Physics. Electrodynamics classes". G. Ya. Myakishev “Physics. Electrodynamics classes". Magazine "Kvant". Magazine "Kvant".

Slide presentation

Slide text: Conductors and dielectrics in an electrostatic field Artem Mezhetsky 10 “B” Performed by: Municipal educational institution “Secondary school No. 30 of the city of Belovo” Head: Popova Irina Aleksandrovna Belovo 2011

Slide text: Plan: 1. Conductors and dielectrics. 2. Conductors in an electrostatic field. 3. Dielectrics in an electrostatic field. Two types of dielectrics. 4.Dielectric constant.

Slide text: substances by conductivity conductors are substances that conduct electric current there are free charges dielectrics are substances that do not conduct electric current there are no free charges

Slide text: Structure of metals + + + + + + + + + - - - - - - - - -

Slide text: Metal conductor in an electrostatic field + + + + + + + + + - - - - - - - - + + + + + Ev. Evn. Evn. = Evn. -

Slide text: Metal conductor in an electrostatic field E external = E internal. Total=0 OUTPUT: There is no electric field inside the conductor. The entire static charge of a conductor is concentrated on its surface.

Slide text: Structure of a dielectric, structure of a molecule of table salt NaCl, electric dipole - a combination of two point charges, equal in magnitude and opposite in sign. Na Cl - - - - - - - - + - + -

Slide text: Types of dielectrics Polar Consist of molecules in which the centers of distribution of positive and negative charges do not coincide; table salt, alcohols, water, etc. Non-polar Consist of molecules in which the centers of distribution of positive and negative charges do not coincide. inert gases, O2, H2, benzene, polyethylene, etc.

Slide text: Structure of a polar dielectric + - + - + - + - + - + -

Slide No. 10

Slide text: Dielectric in an electric field + - + + + + + + + - E ext. E internal + - + - + - + - E internal.< Е внеш. ВЫВОД: ДИЭЛЕКТРИК ОСЛАБЛЯЕТ ВНЕШНЕЕ ЭЛЕКТРИЧЕСКОЕ ПОЛЕ

Slide No. 11

Slide text: Dielectric constant of the medium - characteristic of the electrical properties of the dielectric E Eo - electric field strength in a vacuum - electric field strength in the dielectric - dielectric constant of the medium = Eo E

Slide No. 12

Slide text: Dielectric constant of substances substance Dielectric constant of the medium water 81 kerosene 2.1 oil 2.5 paraffin 2.1 mica 6 glass 7

Slide No. 13

Slide text: Coulomb's Law: Electric field strength created by a point charge: q1 q2 r 2 q r 2

Slide No. 14

Slide text: Task

Slide No. 15

Slide text: Solving the problem

Slide No. 16

Slide text: Problem solving

Slide No. 17

Slide text: Problem solving

Slide No. 18

Slide text: Test No. 1: A positively charged body is brought to three contacting plates A, B, C. Plates B, C are a conductor, and A is a dielectric. What charges will be on the plates after plate B is completely pulled out? Answer options

Slide No. 19

Slide text: No. 2: A charged metal ball is sequentially immersed in two dielectric liquids (1< 2). Какой из нижеприведенных графиков наиболее точно отражает зависимость потенциала поля от расстояния, отсчитываемого от центра шара?

Slide No. 20

Slide text: No. 3: When the space between the plates of a flat capacitor is completely filled with a dielectric, the field strength inside the capacitor changes 9 times. How many times did the capacitance of the capacitor change? A) Increased by 3 times. B) Decreased by 3 times. C) Increased 9 times. D) Decreased by 9 times. E) Has not changed.

Slide No. 21

Slide text: No. 4: A positive charge was placed in the center of a thick-walled uncharged metal sphere. Which of the following figures corresponds to the distribution pattern of the electrostatic field lines?

Slide number 22

Slide text: No. 5: Which of the following figures corresponds to the distribution of field lines for a positive charge and a grounded metal plane?

Slide No. 23

Slide text: References Kasyanov, V.A. Physics, 10th grade [Text]: textbook for secondary schools / V.A. Kasyanov. – LLC “Drofa”, 2004. – 116 p. Kabardin O.F., Orlov V.A., Evenchik E.E., Shamash S.Ya., Pinsky A.A., Kabardina S.I., Dik Yu.I., Nikiforov G.G., Shefer N. .AND. "Physics. 10th grade”, “Enlightenment”, 2007

Slide No. 24

Slide text: Everything =)

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Conductors in an electric field

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Dielectrics do not conduct electric current under normal conditions. The term "dielectrics" was introduced by Faraday. A dielectric, like any substance, consists of atoms and molecules. Dielectric molecules are electrically neutral. Polarization. Field strength in a dielectric. Under the influence of the field, the dielectric is polarized. The resulting field inside the dielectric. Field. Electrical bias. The external field is created by a system of free electric charges. Gauss's theorem for a field in a dielectric. Gauss's theorem for the electrostatic field in a dielectric. The properties of ferroelectrics strongly depend on temperature. - Dielectric.ppt

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