"Electric Power" Electric Power and Electric Power PPT Courseware 5

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"Electric Power" Electric Power and Electric Power PPT Courseware 5

Review questions:

1. Electric energy is a kind of energy.

(1) Unit: Joule Abbreviation: Joule symbol: J

(2)Kwh, (degree)

1 kilowatt hour = 1 degree

2. Unit conversion: 1kwh=3.6×106J

3. Electrical work—current does work.

The essence of the process of current doing work is to convert electrical energy into other forms of energy.

4. Unit of electrical energy:

Joule (J) degree kilowatt hour (kwh)

1 degree=1kwh=3.6×106J

Electric power

1. Meaning: Indicates the speed of electrical energy consumption by electrical appliances. Symbol: P

Electric power P is not the same as electric energy W

2. Definition: Current consumes electrical energy within unit time (1S)

3. Formula: P=W/t

P - Power of electrical appliance - Watt (W)

W - Electric energy consumed by current - Joules (J)

t - time taken - seconds (S)

4.Unit:

A. The international unit is watt, referred to as watt, and its symbol is W.

B. The common unit is kilowatt (KW). l kilowatt = 1000 watts.

1W=1J/S means that the electric energy consumed by the current in 1S is 1J

5. Understanding of the definition:

(1) This formula applies to all circuits and electrical appliances. But pay attention to the correspondence of each physical quantity.

(2) Formula deformation: W=Pt t=w/p

Explore: How to measure electrical power?

Principle: P=UI

P - Power - Watt (W)

U-voltage-volt (v)

I - Current - Ampere (A)

Example: The electrical power of a household energy-saving fluorescent lamp is 11W. What is the current in milliamps that passes through it during use?

I=p/U=11w/220v=0.05A=50mA

A. The power of electrical appliances at rated voltage is called rated power. In order to use electrical appliances to work normally, the electrical appliances should be used to work at rated voltage.

B. Each electrical appliance has only one rated power, but there are many actual powers.

C. The brightness of the light bulb is only determined by its actual power. (It has nothing to do with its rated power, current, voltage, etc.)

D. The relationship between actual power and rated power:

When U real < U amount, P real < P amount, the electrical appliance cannot work normally;

When U real = U amount, P real = P amount, the electrical appliance works normally;

When U real > U amount, P real > P amount, electrical appliances are easily burned out.

A lamp is connected to a circuit with a voltage of 220V. The current flowing through the lamp is 68mA. How many watts does this bulb have?

Solution: P=UI=220V×0.068mA=15W

Answer: The electric power of this light bulb is 15W.

There is an energy-saving lamp used in a 220V circuit with a power of only 1W. Find the current flowing through it.

Solution: From P= IU we can get:

I=P/U=1W/220V

=4.5 X 10-3A

Answer: The current through it is 4.5 X 10�³A

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For more information about the "Electrical Power, Electrical Power and Electrical Power" PPT courseware, please click on the Electrical Power ppt Electrical Power and Electrical Power ppt tab.

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Update Time: 2024-10-05

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