"How fast or slow the current does work" Current work and electric power PPT courseware

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"How fast or slow the current does work" Current work and electric power PPT courseware

1. Definition and characteristics of electric power

1.Meaning: A physical quantity that represents the work done by electric current_______.

2. Definition: Call ____________________ electrical power.

3. Formula: P=w/t. Commonly used formulas are: P=IU; P=U²/R; P=I²R.

4. Units: _______ and _______, 1 kW = _______W.

5. Experiments show that electric power is directly proportional to _______ and _______. Electric power, etc.

2. Rated power

1. Rated voltage: the voltage when the electrical appliance is working normally.

2. Rated current: the current when the electrical appliance is working normally.

3. Rated power: the power of the electrical appliance when it is working normally.

3. Actual power

The power corresponding to _______ added to the electrical appliance is called the actual power of the electrical appliance.

1. Electric power

(1) Definition: In physics, the electrical work done by electrical appliances per unit time, or the electrical energy consumed by electrical appliances per unit time, is called electrical power, represented by the symbol P.

(2) Formula: P=W/t; the units used for each physical quantity in the formula are: W, J, s.

(3) Factors affecting size: voltage, current. Accurate experiments show that electric power is equal to the product of voltage U and current I, that is, P=UI, where the unit of U is V, the unit of I is A, and the unit of P is W.

[Example 1] The correct statement about electrical power is ()

A. The greater the electrical energy consumed by an electrical appliance, the greater the electrical power.

B. The less time it takes an electrical appliance to consume electrical energy, the greater its electrical power.

C. The faster an electrical appliance consumes electric energy, the greater the electric power.

D. None of the above statements are correct

Tip: The electrical power of an electrical appliance is large, which means that the electrical appliance consumes electric energy quickly or the current does work quickly. It cannot be understood that the current does more work. Electrical power can also reflect the effect produced by electrical appliances when they pass through current. For example, if the electric power of a light bulb is large, it means that the current does more work through the light bulb per unit time, that is, more electric energy is consumed per unit time, and the brightness of the light bulb will be greater.

[Example 2] The nameplates of two ordinary lighting bulbs A and B are as shown in the figure. Which of the following statements is correct ()

A. When both lamps emit light normally, lamp B consumes more power.

B. When both lamps emit light normally, the resistance of lamp A is smaller than the resistance of lamp B.

C. Two lamps are connected in series in a 220 V circuit. Lamp A is brighter than lamp B.

D. Connect lamp B to the 110 V circuit, its actual power is 50 W

Tip: Rated voltage and rated power are usually marked on electrical appliances. When the filament remains unchanged, the current and resistance during normal operation can be calculated using the deformation formula of P=UI.

Knowledge point 1: Understanding of electrical power

1. When the following household appliances are working normally, the electric power is approximately 1 kW ()

A. Microwave oven B. Refrigerator

C. Electric fan D. Television

2. A fire broke out in a factory in Hangzhou City, Zhejiang Province. The fire was caused by a line failure. An important cause of line failure is poor contact at the connection point of the line. When the connection point of the line connection is in poor contact, the resistance there will be greater than if the line is intact. The value will increase, and the electric power consumed there will ________ (fill in "decrease", "increase" or "unchanged"), which may cause local overheating and cause fire.

Knowledge point 2 Rated voltage, rated power

3. The electrical power of household appliances marked with "220 V 100 W" when operating normally ()

A. Greater than 100 W B. Less than 100 W

C. Equal to 100 W D. Its power cannot be calculated

4. The filament resistance of an electric lamp when it is not connected to the circuit is 55 Ω. When it is connected to a 220 V power supply and lights normally, the current flowing through it is 0.5 A. Then the rated power of the lamp is W; from the moment the power is turned on to the normal lighting process, the maximum power of the lamp is ______W.

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"How fast electric current does work" Current work and electric power PPT courseware 3:

"How Fast or Slow Electric Current Does Work" Current Work and Electric Power PPT Courseware 3 The aluminum plate on the electric energy meter in our home sometimes moves slowly, sometimes in a hurry. why? What does the rotation speed of the aluminum disk have to do with it? The aluminum disk rotates at different speeds, indicating how quickly the electrical appliance consumes electricity..

"How fast electric current does work" Current work and electric power PPT courseware 2:

"How fast electric current does work" Current work and electric power PPT courseware 2 Knowledge review: What is electric power? What are its two units? What's the conversion relationship? The work done by current is called electrical work; the units include joules and degrees; 1 degree = 1 kilowatt hour, 1 degree = 3.6106 joules..

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Update Time: 2024-07-29

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