"Conductive Properties of Different Materials" Simple Circuit PPT Courseware 6

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"Conductive Properties of Different Materials" Simple Circuit PPT Courseware 6

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conductor

Object that defines ________. Such as metals, aqueous solutions of various acid and alkali salts, the human body, the earth

Reasons for conducting electricity: Conductors conduct electricity easily because there are a large number of _______ charges in the conductor.

insulator

Object that defines ________. Such as rubber, glass, ceramics, plastic, oil

The reason why it is not easy to conduct electricity

The reason why insulators are not easy to conduct electricity is that the charges inside the insulator can move freely, and the charges are almost all bound within the range of ________

Semiconductors are classified according to the conductive properties of materials. In addition to conductors and insulators, there is also a type of material whose conductive properties are between conductors and insulators. This type of material is called ______. Germanium, silicon, gallium arsenide, etc. are all semiconductors

resistance

Definition: The effect of a conductor on current _______

Unit The unit of resistance is _____, abbreviated as ohm, symbol Ω. Commonly used units include _____ and _____. The conversion relationship is 1 MΩ=_____ kΩ,1 kΩ=_____ Ω

Conductors and Insulators

Objects that easily conduct electricity are called conductors. Metals, human bodies, earth, graphite, and aqueous solutions of acid, alkali and salts are all conductors. Conductors are important electrical materials. The core of wires must be made of metal because metal is a conductor and can easily conduct electricity. Conductors conduct electricity easily because there are a large number of freely moving charges in the conductor, and these charges can move from one place in the conductor to another. In metal conductors, some electrons can leave the confines of the atomic nucleus and move freely inside the metal, becoming free electrons. Therefore, metals conduct electricity by free electrons. The aqueous solution of acid-base salts contains a large number of positive and negative ions, which can move freely in the solution. Therefore, the aqueous solution of acid-base salts relies on these positive and negative ions to conduct electricity.

Objects that are not easy to conduct electricity are called insulators. Rubber, glass, ceramics, plastics, oil, pure water, dry air, etc. are all insulators. Insulators are also important electrical materials. The core of the wire must be wrapped with a layer of rubber or plastic. Because they are insulators, they are not easy to conduct electricity and can prevent leakage. Insulators are not easy to conduct electricity because the charges in the insulator are almost bound within the atomic range and cannot move freely, that is, there are almost no free-moving charges inside the insulator.

[Example] Which of the following statements is correct ()

A. There are free electrons in metal conductors, so the number of negative charges in metal conductors is more than the number of positive charges.

B. When a metal conductor conducts electricity, it will become an insulator after consuming all the free electrons.

C. Rubber is an insulator, but it becomes negatively charged after being rubbed with fur. With the extra electrons, it becomes a conductor.

D. There are free electrons in metal conductors. Metals lose free electrons and become positively charged, but metals may also be negatively charged.

Analysis: According to the theoretical knowledge of the nuclear structure of atoms, when an object is in an electrically neutral state, the number of positive and negative charges is equal, so option A is wrong; the metal conduction process itself does not consume electrons, and metal is still a conductor, so option B is wrong ; After rubber is negatively charged, the electrons outside its atomic nucleus are still bound within the atomic range and cannot move freely. Rubber is still an insulator. Option C is wrong. Metals become positively charged after losing electrons, and become negatively charged after gaining electrons. Option D correct.

1. Which of the following objects are usually conductors ()

A.Iron, ceramics, glass B.Graphite, oil, earth

C. Plastic, dry wood, rubber D. Mercury, human body, earth

2. When a classmate was connecting a circuit, half of the wires were not enough. Please think about it. Using one of the following materials instead of wires can also make a small light bulb shine. This material is ()

A. Copper wire B. Cotton wire C. Plastic D. Rubber

3. The reason why conductors can conduct electricity is ()

A. There are many electrons in the conductor

B. There are many charges in the conductor

C. There are many positive and negative charges in the conductor

D. There are many free charges in the conductor

4. Xiaoqing divided the following items into two categories: ① pencil lead, copper wire, salt water; ② plastic ruler, eraser, oil. The items he divided into two categories belong to ()

A. Solids and liquids B. Conductors and insulators

C. Metals and non-metals D. Crystals and amorphous

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Update Time: 2024-10-20

This template belongs to Physics courseware Beijing Normal University Ninth Grade Physics Volume 1 industry PPT template

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