"Current and Circuits" Current and Circuit PPT Teaching Courseware

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"Current and Circuits" Current and Circuit PPT Teaching Courseware

Part One: Knowledge Management

1. current

Formation: Charge _______ forms an electric current.

Direction: The direction of ______ directional movement is specified as the direction of current flow.

Note: Outside the power supply, the direction of current flows from the positive electrode to the negative electrode, and the direction of electron movement is opposite to the direction of the current.

2. circuit

Definition: Power supply, electrical appliances, plus wires, and often switches, form a path through which current can flow, called a circuit.

Composed of: power supply, ______, wires and ______.

3. dry cell battery

Function: A common power supply, a device that provides electrical energy.

Positive electrode: The end with the metal cap.

Negative pole: The end without the metal cap.

4. circuit status

Path: A circuit that is normally connected, that is, a circuit that electrical appliances can work on.

Open circuit: If the circuit is cut off somewhere, there will be no current flowing in the circuit. For example, if the switch is disconnected, the filament is broken, or the contact is poor, it is an open circuit.

Short circuit: Directly connect the positive and negative poles of the power supply or both ends of the electrical appliance with wires to form a short circuit. The former is called a short circuit in the power supply, and the latter is called a short circuit in the electrical appliance. When the power supply is short-circuited, the current is very large, and the power supply and wires will be damaged; when the electrical appliance is short-circuited, the short-circuited electrical appliance cannot work.

Note: The condition for obtaining continuous current is that there is a power supply and the circuit is a path.

5. Circuit diagram

Definition: A diagram that uses ______ to represent circuit connections is called a circuit diagram.

Note: Circuit diagrams are generally rectangular, with wires running horizontally and vertically, and components distributed evenly. Do not draw them at the corners.

Current and circuit PPT, part 2 content: classification and exploration

One type of circuit connection

[2017•Shandong Zaozhuang]As shown in the picture, the circuit diagram consistent with the actual product is ()

[Analysis] Analysis of the physical diagram shows that the current starts from the positive electrode, passes through the ammeter, bulb L1, switch, and bulb L2 and returns to the negative pole. The voltmeter is connected to both ends of L1. Picture B is consistent with the actual picture; the connection of the two light bulbs in Picture A is inconsistent with the actual picture; the voltmeter in Figure C is connected to both ends of L2, which is inconsistent with the actual picture; the voltmeter in Figure D is connected to both ends of the power supply, which is inconsistent with the actual picture. Choose B.

[Summary] A circuit refers to a current path formed by connecting a power supply, electrical appliances, and switches with wires. Therefore, a complete circuit includes a power supply, electrical appliances, switches, and wires. The key to answering such questions is to analyze the physical diagram. The connection status of each electrical appliance in the circuit is the focus and difficulty of this question. The next step is to test the judgment of the correct drawing method of the circuit diagram.

Type 2: Identify the three states of the circuit

[2017•Guangxi Liuzhou]In the circuit shown in the figure, after the switch S is closed, both light bulbs glow ()

[Analysis] After the switch in picture A is closed, a power short circuit occurs and neither lamp can illuminate, so A is wrong; after the switch in picture B is closed, both bulbs can light up, so B is correct; after the switch in picture C is closed, the left The light bulb L1 is short-circuited, and only L2 emits light, so C is wrong; after the switch in Figure D is closed, the light bulb L1 on the left is short-circuited, and only L2 emits light, so D is wrong.

[Summary] A short circuit will cause great harm, so when connecting the circuit, be careful not to short circuit to avoid damage to the power supply and electrical appliances; there are two main types of short circuits: one is a short circuit in the power supply, which will cause the power supply to burn out; The electrical appliance cannot work; the second is that the electrical appliance is short-circuited, which will cause the short-circuited electrical appliance to not work.

Current and circuit PPT, the third part: evaluation in class

1.[2017•Shandong Jinan]As shown in the picture, it is an automatic protection device in the electric fan. When the fan is accidentally bumped and tilted or tipped over, the ball will roll to one side to disconnect the circuit and protect the fan. From this, it can be judged that the role of this protection device in the fan circuit is equivalent to ()

A. switch b. wire

C. Power supply D． Electrical appliances

2. [2018•Guangdong Shenzhen]When an electrical appliance is connected to the positive and negative terminals of the battery, the correct direction of the current is ()

A. Positive pole → electrical appliance → negative pole

B． Electrical appliance → positive pole → negative pole

C. Negative pole → electrical appliance → positive pole

D． Positive pole→negative pole→electrical appliance

3.[2018•Zhejiang Wenzhou]The following physical connections are consistent with the circuit diagram (the copper sheet of the fruit battery is the positive electrode and the zinc sheet is the negative electrode)()

4.[2019•Wuxi, Jiangsu]An experimental team used two identical small light bulbs to connect the circuit as shown in the picture. When the switch was closed, it was found that neither light A nor light B was on. In order to find Xiao Zhang used a wire to check the cause of the fault. When the wire is connected to two points AB, light A is off and light B is on; when the wire is connected to two points BC, neither light is on. It is inferred that the fault is ()

A. There is a short circuit between two points AB

B． There is a circuit break between two points AB

C. There is a short circuit between two points BC

D． There is a circuit break between two points BC

5. [2019•Anhui Xiuning]In the circuit shown in the figure, under the following circumstances, the correct one is ()

A. When K1 and K2 are both disconnected, L1 and L3 are both on, but L2 is off.

B． When K1 and K2 are both closed, L1, L2 and L3 all light up

C. When K1 is open and K2 is closed, both L2 and L3 will light up, but L1 will not light up.

D． When K1 is closed and K2 is open, both L1 and L2 will light up, but L3 will not light up.

Current and circuit PPT, part 4: layered work

1.[2018•Hebei Baoding]As shown in the picture, a portable charger is charging a mobile phone battery. During the charging process, the mobile phone battery is equivalent to () in the circuit

A. Power supply b. switch

C. Wire D. Electrical appliances

2. [2019•Tianjin Binhai]The arrow as shown in the picture indicates the direction of current, and the correct one is ()

3. [2018•Guangzhou, Guangdong]The circuit diagram with the following options and the same connection method as the circuit shown in the figure is ()

4. [2018•Nanjing, Jiangsu]For the three circuits shown in the figure, the correct state judgment is ()

A. A open circuit, B short circuit, C open circuit

B． A path, B short circuit, C short circuit

C. A is open circuit, B is connected, C is short circuit

D． A short circuit, B open circuit, C open circuit

5. [2019•Shandong Linyi]As shown in the picture, the sweet and sour fruit lights up a row of light-emitting diodes. In this simple circuit, the fruit is equivalent to ______. If you want to control the flow of this circuit If the circuit is broken, ______ should also be installed in the circuit.

6. [2019•Shandong Linyi] Small windmills as shown in the picture are often seen on the roadside telephone poles. Xiaochuan asked the staff of the power supply plant, and the answer he received was: because birds often carry back wires, etc. Conductive materials build nests. Once the iron wire is placed on the line, it is easy to cause accidents. Small windmills are placed to drive away birds. Do you think the accident may be caused by ______ (optional "short circuit" or "open circuit").

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Update Time: 2024-11-24

This template belongs to Physics courseware People's Education Edition Ninth Grade Physics Complete Book industry PPT template

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