"What is Electricity" Understanding Circuits PPT Courseware

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"What is Electricity" Understanding Circuits PPT Courseware

1. Electricity and our lives

Electricity is closely related to our lives, and our study and life are inseparable from electricity. With the rapid development of science and technology, the development of high and new technologies is inseparable from electricity.

2. Two kinds of charges

1. Frictional electrification: Some objects can ______ small objects after being rubbed. People say that these rubbed objects are charged with "electricity", or they are charged with ______.

2. Types of charge

(1) The charge on the ______ that has been rubbed by silk is defined as ______ charge.

(2) The charge on ______ that has been rubbed by fur is defined as ______ charge.

3. The law of interaction between two kinds of charges: the same kind of charges ______ each other, and the different kinds of charges ______ each other.

3. Understand triboelectricity from the perspective of microscopic particles

1. The structure of an atom: An atom is composed of ______ and ______ located in the center of the atom. ______ in the nucleus has a positive charge, and ______ has a negative charge.

2. The essence of triboelectricity: Triboelectricity is not actually the generation of electricity, but the ______ of electrons between objects.

3. Electrostatic induction: When a charged object and an uncharged conductor are close to each other, due to the interaction between charges, the charges inside the conductor will be redistributed. Different kinds of charges are ______ to the vicinity of the charged object, and the same kind of charges are ______ _____ to the other end of the conductor away from the charged body. This phenomenon is called electrostatic induction.

1. Frictional electrification

(1) Phenomenon: After an object is rubbed, it can attract light and small objects.

(2) Essence: transfer of electrons.

(3) Reasons why objects are charged: ① Negative charge: The atoms of the object obtain electrons from the outside due to friction or other reasons. Atoms carry more negative charges than positive charges. ② Positively charged: The atoms of the object lose electrons, and the number of negative charges carried by the atoms is less than the number of positive charges.

[Example 1] People stipulate that a glass rod rubbed with silk is ______ charged because the glass rod ______ (fill in "gain" or "lost") electrons during the friction process.

Tip: The essence of frictional electrification is the transfer of electrons, causing the atoms of the object to gain (excess) or lose (lack of) electrons. Objects that gain electrons become negatively charged due to excess electrons; objects that lose electrons become positively charged due to lack of electrons.

Analysis: The glass rod rubbed with silk is positively charged, indicating that the glass rod loses electrons during the friction with silk.

2. Methods to check whether an object is charged

(1) Utilize the property of charged bodies to attract light and small objects.

Method: Bring the object close to a light and small object (such as small scraps of paper, etc.). If the two attract each other, it proves that the object is charged.

(2) Utilize the law of interaction between charges.

Method: Put the object close to the known charged body. If the object and the known charged body attract each other, it means that the object and the known charged body have opposite electrical properties or the object is not charged; if the object and the known charged body repel each other, it means that the object and the known charged body are mutually repulsive. It is known that the electrical properties of charged objects are the same.

(3) Use an electroscope.

Method: Touch the object to be measured to the metal ball of the electroscope. If the two metal foils of the electroscope open, it proves that the object to be measured is charged.

Knowledge point 1: Frictional electrification phenomenon

1. Which of the following phenomena has nothing to do with frictional electrification ()

A. Plastic can attract small scraps of paper after rubbing against hair.

B. After the book is soaked with water, all the papers inside stick together.

C. Amber can attract paper scraps after rubbing against wool fabrics

D. The chemical fiber clothes you wear can easily absorb dust.

2. Which of the following statements is correct ()

A. Neutral atoms are uncharged because the positive and negative charges inside the atom cancel each other out, and there is no charge in the object.

B. The object is positively charged because there are no electrons in the object

C. Triboelectricity uses friction to separate positive and negative charges.

D. Objects whose nuclei have strong ability to bind electrons will not be charged.

3. We often see an eye-catching warning at gas stations: "It is strictly prohibited to use plastic barrels to transport gasoline." This is because during transportation, gasoline will continue to rub against the barrel wall, causing the plastic barrel to become _______, creating a fire hazard.

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For more information about the PPT courseware "Understanding What Electricity Is a Circuit", please click the "Understanding What Electricity Is a Circuit ppt" ppt tag.

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Update Time: 2024-10-02

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