"Household Circuit" Daily Electricity PPT Download

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"Household Circuit" Daily Electricity PPT Download

Part One: Knowledge Management

1. Home circuit composition

House entrance wires: One is called the neutral wire, the other is called the live wire. There is a voltage of 220 V between the live wire and the neutral wire.

Electric energy meter: measures and records the electric energy consumed by the user.

Main switch: controls the on and off of the circuit to facilitate circuit maintenance and equipment replacement.

Safety device: When the current in the circuit is too large, it automatically cuts off the circuit to protect the circuit. Installed behind the knife switch.

Socket: connected in parallel in the circuit, the connection method of the three-hole socket is "zero on the left, fire on the right, and ground on the top".

Note: The top metal of the screw-top bulb should be connected to the switch, and the side screw should be connected to the neutral wire. In this way, when the switch is turned off, the bulb can be disconnected from the live wire and people will not get electric shock.

2. Test pen

Function: Identify the live and neutral wires in household circuits.

Structure: It consists of a pen tip metal body, a resistor, a neon tube, a spring and a pen tail metal body.

Usage: Touch the metal body at the end of the pen with your hand, and the tip of the pen touches the wire (or a conductor connected to the wire). If the neon tube lights up, it means it is touching the live wire; if the neon tube does not light up, it means it is touching the neutral wire.

3. three pin plug

as the picture shows:

One of them is connected to the live wire and is marked "L"; one is connected to the neutral wire and is marked "N"; the third one is marked "E" and is connected to the metal shell of the electrical appliance. Its function is to connect the shell and power supply of the electrical appliance in case of an emergency. If the insulation between the live wires is damaged, the shell will be charged, and the current will flow into the earth without causing harm to the human body.

4. leakage protector

Under normal circumstances, electrical appliances form a closed circuit through the live wire, neutral wire and the power supply in the power supply system, and there should be no current flowing directly into the earth. However, if a person standing on the ground accidentally touches a live wire and the current flows into the earth through the human body, the leakage protector will quickly cut off the current to protect the person.

Household circuit PPT, part 2: classification and exploration

Type 1: Composition of household circuits

[2017•Tianjin]In home circuits, the following components must be installed in sequence from the time you enter the home and then connected to electrical appliances. The correct order is (B)

A． Electric energy meter, fuse, main switch

B． Electric energy meter, main switch, fuse

C. Safety device, energy meter, main switch

D. Main switch, energy meter, fuse

[Analysis] The electric energy meter measures the amount of electric energy consumed by the entire home circuit and must be installed at the front. The main switch controls the entire circuit. In order to facilitate circuit maintenance, it must be installed behind the energy meter. Excessive current in the circuit will blow the fuse. In order to make it easier to replace the fuse, the fuse is installed behind the main switch. So choose B.

[Method Summary] How to connect household circuits: electrical appliances are connected in parallel, sockets and electrical appliances are also connected in parallel; the switch is connected to the live wire, and the left zero and right fire are connected to the ground wire.

Type 2: Household circuit fault analysis

[2018•Bayannur]In the household circuit as shown in the figure, when the switch S is closed, the light bulb L does not light up. When testing points c and d with a test pen, the neon tubes both glow. When testing a At two points, b and b, only the neon tube at point a emits light, then the fault may be (　A　)

A． There is a circuit break somewhere between b and c

B． There is a circuit break somewhere between a and d

C. Short circuit between live and neutral wires

D. The lamp filament is broken

[Analysis] As shown in the figure, after closing the switch, it is found that the lamp L does not light up. When using a test pen to test points c and d, the neon tubes both glow, indicating that both c and d are connected to the live wire (that is, the circuit between point c and the live wire is not connected) Open circuit); when testing points a and b, only the neon tube at point a glows, and the neon tube at point b does not glow, indicating that point b is not connected to the live wire, so the fault may be an open circuit somewhere between b and c, so A Correct, B and D are wrong; if the live wire and neutral wire are short-circuited, the fuse will blow or the air switch will trip, and the entire circuit will be disconnected. When testing each point with a test pen, the neon tube will not emit light, so C is wrong.

[Method summary] When the circuit is open, the light bulb cannot light; when the circuit is short-circuited, the light bulb cannot light; when the circuit is open, if the voltage at both ends of the light bulb is too low, the light bulb cannot light either.

Household circuit PPT, the third part: evaluation in class

1. [2018•Jilin Changchun]In the home circuit shown in the picture, the incorrectly connected component is (B)

A． switch b. two hole socket

C. electric light d. three hole socket

2. [2018•Zhuzhou, Hunan]The picture shows the structure and usage of the test pen. Which of the following statements is correct (B)

A． A test pen can determine whether an object is positively or negatively charged

B． If the neon tube glows, it means that the human body has become a path for electric current.

C. The pen tip, resistor and neon tube are conductors, and the shell, spring and pen card are insulators

D. Among the two methods of using the test pen, A is correct and B is wrong.

3. [2017•Anhui]The picture shows a home circuit with a leakage protector installed. When the leakage protector detects that the currents passing through points A and B in the figure are not equal (that is, leakage occurs), it will quickly cut off the circuit to protect it. Places A and B are equipped with electrical appliances and switches respectively. For this circuit, which of the following statements is correct (D)

A． Electrical appliances should be installed in place A, and switches should be installed in place B.

B． The circuit is equipped with a leakage protector, so you don’t need to disconnect the power supply to replace the bulb.

C. If a home appliance repairman accidentally gets an electric shock at point C in the picture, the leakage protector will not cut off the circuit.

D. If the resistance of the human body is 10 kΩ, the current flowing through the human body during an electric shock is 22 mA

Household circuit PPT, part 4: layered homework

1. [2019•Shandong Dezhou]The home circuit designed by Xiao Ming is as shown in the figure. The correct design is (　D)

A． socket d

B． switch c

C. electric light b

D. socket a

2. [2018•Hubei Suizhou]In the household circuit as shown in the picture, when the switches are closed, the light L does not light up. Use a test pen to test the left and right holes of the socket. The neon tubes all glow, and the circuit There is only one fault. The following statement about the circuit diagram and the fault is incorrect (D)

A． The unit of the electric energy meter is kilowatt hours

B． The three-hole socket is to prevent electric shock accidents caused by electrified electrical casings.

C. If a light bulb L1 is connected between wires a and b, then it and L are connected in parallel

D. According to the test results, there should be an open circuit between m and j

[Analysis] An electric energy meter is an instrument that measures the electric energy consumed by electrical appliances. The unit is kilowatt-hours, so statement A is correct; there is an extra hole specifically for grounding in the three-hole socket to connect the metal shell of the electrical appliance to the earth. When the electrical appliance shell is charged, the current is introduced from the ground wire to the earth, which can prevent the occurrence of electric shock accidents, so statement B is correct; if a light bulb L1 is connected between wires a and b, that is, L1 is connected between the live wire and the neutral wire, it and L are connected in parallel, so statement C is correct; when the switches are closed, the light L does not light up, indicating that there may be an open circuit fault in the circuit; use a test pen to test the left and right holes of the socket, and the neon tubes both glow, indicating that m and j They are all connected to the live wire, so the fault is that the neutral wire on the left side of m is open, so D's statement is wrong.

3. [2018•Jingzhou, Hubei]The lights at a classmate's home were working normally. When he inserted the "220 V 16 W" desk lamp into the socket and turned on the desk lamp switch, all the indoor lights went out. This phenomenon occurred. The reason may be (B)

A． Short circuit at the socket B. Short circuit at the lamp head of the desk lamp

C. Open circuit at the socket D. Broken circuit at desk lamp head

[Analysis] All the indoor lights went out, indicating that the fuse on the main circuit was blown, which was caused by excessive current in the circuit. If there is a short circuit at the socket, then the fuse is blown before inserting the desk lamp and other lamps will not light up, so A is wrong; if there is a short circuit at the lamp head of the desk lamp, then when the desk lamp plug is inserted into the socket and the switch of the desk lamp is turned on, a short circuit occurs in the circuit. Therefore, B is correct; if there is an open circuit at the socket, it will not cause a short circuit and blow the fuse before the desk lamp is plugged in, so C is wrong; if there is an open circuit at the lamp head of the desk lamp and the switch of the desk lamp is turned on, the desk lamp will not shine, but all the indoor lights will shine, so D mistake.

4. [2019•Shandong Linyi]Which of the following statements is correct (B)

A． The voltage of domestic circuits in our country is 110 V

B． A test pen can be used to identify live and neutral wires

C. Only 36 V voltage is safe for the human body

D. Electrical appliances in household circuits are all connected in series

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Update Time: 2024-10-01

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