"Household Electricity" Exploring Circuit PPT Courseware 2

"Household Electricity" Exploring Circuit PPT Courseware 2

Teaching objectives knowledge and skills

1. Observe and understand the composition and connection methods of household circuits, and cultivate students' observation and analysis abilities.

2. Know the live and neutral wires.

3. Understand the knowledge of safe use of electricity in life and cultivate awareness of safe use of electricity.

4. Process and method: Through experimental exploration, know how to use a test pen to identify the live wire and the neutral wire.

5. Emotional attitudes and values: Enable students to have awareness of safe use of electricity and a sense of social responsibility, and be able to consciously implement and promote safe use of electricity.

home circuit

1. Entrance wire: There are usually two wires connected to the outdoor power supply circuit, one is the live wire and the other is the neutral wire. The voltage between the live wire and the neutral wire is 220V

2. The ground wire is not connected to the outside entrance wire, but is connected to the ground conductor buried in the earth in the residential building.

3. The voltage used in household circuits is 220V (my country’s household power voltage)

4. Household circuits are alternating current

1. Composition of household circuits

1. There are two entrance lines (power lines):

2. Electric energy meter: An instrument that measures the user’s energy consumption over a period of time. Installed on the trunk line of household circuits

3. Knife switch: Installed behind the electric energy meter, it is the main switch of the household circuit. There is a fuse at the lower end.

4. Fuse: The material is composed of lead-antimony alloy with high resistivity and low melting point, and is connected in series in the circuit. When the current is too large, the circuit is automatically cut off.

Use a test pen to identify the live and neutral wires

1. The structure of the electric test pen:

It is composed of a metal pen tip, a large resistor, a neon tube and a metal body at the tail of the pen connected in sequence.

2. How to use the electric test pen:

Hold the metal body at the end of the pen with your hand and touch the tip of the pen to the incoming wire. If it touches the live wire, the neon tube will glow. If the pen tip touches the neutral line, the neon tube will not glow.

2. Electric lights

Electric lights mainly include incandescent lamps, fluorescent lamps, and high-pressure gas lamps.

Why do electric lights glow?

Because the tungsten filament in the bulb heats up when energized, the filament reaches about 2000°C and reaches the incandescent state, so the filament emits bright white light.

The socket can be connected to various electrical appliances, which is very convenient and flexible.

think about it

1. What is the connection relationship between the various electrical appliances on the socket? in parallel

2. Which two wires are the extensions of the two wires on the socket?

Neutral and live wires

3. Where is the third wire of the three-hole socket connected? What does it do?

Ground; prevent electric shock

4. Refrigerator wiring diagram

3. Safe use of electricity

1. Electric shock accidents in household circuits are caused by the human body's direct or indirect contact with live wires.

2. Two forms of high-voltage electric shock

what can we do about it?

1. Cut off the power supply as soon as possible, or use dry wooden sticks or bamboo poles to jump the wires so that the person who is electrocuted can quickly disconnect from the power supply. (in the wild)

2. Provide artificial respiration if necessary, and call 120 to notify medical personnel for rescue.

Summary of key points

1. How to prevent electric shock and ensure safe use of electricity?

(1) The installation of household circuits should meet the requirements for safe electricity use;

(2) Be careful not to get electrical appliances wet;

(3) Protect the insulator of electrical appliances and prevent their live wires from being exposed;

(4) For household appliances with metal casings, the casings must be grounded;

(5) Do not approach high-voltage charged objects outdoors.

2. Principles of safe electricity use:

(1) Do not come into contact with low-voltage charged objects;

(2) Do not go close to high-voltage charged objects.

3. Causes of excessive current in household circuits

(1) Short circuit; (2) The total power of electrical appliances is too large.

Practice, you can do it

1. As shown in Figure 1, after closing the switch S, it was found that the lamp L did not light up and the fuse was not blown. A classmate used a test pen to test the two wires C and D of the lamp head and found that both of them made the test pen glow. When the test pen is used to test the live wire A and the neutral wire B, although it can light up when measuring the live wire A, it does not light up when measuring the neutral wire B, then it can be determined that the fault is ()

A. Short circuit between live and neutral wires

B.Lamp L is short-circuited

C. There is a break somewhere in the AC section of the wire

D. There is a break somewhere in the BD section of the wire

2. Which of the following practices conforms to the principle of safe electricity use ( )

A. Insert the power plug with wet hands

B． For electrical appliances with metal casings, the power plug should be a three-pin plug.

C. When someone gets an electric shock, you should immediately pull the person away with your hands

D． The power plugs of many high-power electrical appliances are plugged into the same power strip and work simultaneously.

3. The lights in a classmate’s home used to glow normally. When a desk lamp plug with the switch turned off was inserted into the socket, the fuse blew and all the indoor lights went out. The reason may be ( )

A. The power of the desk lamp is too high. B. The bulb in the desk lamp is short-circuited.

C. The socket was short-circuited D. The plug of the desk lamp was short-circuited

Keywords: Exploring Circuit Teaching Courseware, Home Electricity Teaching Courseware, Shanghai Science Edition 9th Grade Physics PPT Courseware Download, 9th Grade Physics Slide Courseware Download, Exploring Circuit PPT Courseware Download, Home Electricity PPT Courseware Download, .PPT format ;

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