"Understanding Electric Power" Electric Energy and Electric Power PPT Courseware 2

Description

"Understanding Electric Power" Electric Energy and Electric Power PPT Courseware 2

teaching objectives

1. Understand electrical power with examples and know the units of electrical power.

2. Know the relationship between electric power, current and voltage, and be able to apply formulas for simple calculations.

Detection Preview 1

Understand electrical power with examples and know the units of electrical power.

Start by understanding the nameplate of electrical appliances

Activity 1: Observe the nameplate of the appliance

There are some numerical values ​​marked on the nameplates of the electrical appliances we use:

7W, 40W, 1200W on the nameplate...do they have any meaning?

Through the following study, we will understand it!

Activity 2: Understand electrical power

Two light bulbs marked "220V, 25W" and "220V, 100W" are connected to the household circuit at the same time. Which light bulb is brighter?

This shows that in the same period of time, different electrical appliances generally consume different amounts of electricity.

Therefore, some electrical appliances consume electric energy at a fast and some slow speed. When people choose electrical appliances, they pay more attention to the speed of the current doing work.

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

Nameplate meaning

When the light bulb is working normally, the current passing through the filament does 7J of work per second.

When the electric iron is working normally, the current passing through the iron does 1200J of work per second.

Deformation formula of P=W/t

① W=P t

This formula is used to calculate the amount of electrical power (electric energy consumed) and is very useful.

② t=Ｗ/Ｐ

Detection Preview 2

The relationship between electric power, current and voltage can be calculated simply by applying formulas.

Explore what factors are related to the electrical power of light bulbs

Conjectures and Assumptions

Some people say: It has something to do with voltage. The higher the voltage, the greater the electrical power.

Some people say: It has something to do with current. The greater the current, the greater the electrical power.

what you think?

Plan and design experiments

hint:

When studying the relationship between electric power and current, we should try to control the voltage to remain constant.

When studying the relationship between electric power and voltage, we should try to control the current constant

Please design the experimental circuit, select experimental equipment, and draw the experimental circuit diagram.

Conduct experiments and collect data

Please conduct experiments according to the circuit diagram you designed, and fill in the table with the data you collected and the phenomena you observed.

Experiment 1: When the currents of the two lamps are the same:

Experiment 2: When the voltages of the two lamps are the same:

practise

1. Among the statements about electric work and electric power, which one is correct ( )

A. The more work the current does, the greater the electrical power.

B. The longer the current takes to do the same work, the greater the electrical power.

C. The shorter the time the current does work, the greater the electrical power.

D. In the same time, the more work the current does, the greater the electrical power.

2. When a radio operates at a voltage of 6V, the average operating current is 60mA. What is the power of the radio?

Solution: 60mA=0.06A

P=UI

=6V×0.06A

=0.36W

Answer: The power of the radio is 0.36W.

calculate

⑴ When the voltage across an electric heater is 220V, the current flowing through it is 1.5A. How long does it take to power on before it consumes 2.2kwh of electricity?

⑵ The dial of an electric energy meter is marked with "1200r/(kwh)". An electrical appliance is connected to the meter alone. After the electrical appliance works for 4 minutes, the electric energy meter turntable rotates 55r. If the rated voltage of the electrical appliance is 220V, please pass The current of the electrical appliance.

⑶It is known that the voltage applied to both ends of the toy motor that drives a small fan is 1.5V, and the current flowing through the motor is 0.5A. If 60% of the electrical energy consumed is converted into mechanical energy for the rotation of the impeller, how much mechanical energy can be obtained after energizing for 1 minute?

⑴Solution: Known: U=220V I=1.5A

W=2.2kWh=2.2×3.6×106 J

=7.92×106J

According to the electric power formula W=UIt, we can get

Therefore, the electric heater needs to be powered on at 220V for about 6.67h to consume 2.2kWh of electricity.

summary

1. Understanding electrical power

1. Electric power is a physical quantity that expresses how quickly an electric current does work.

2. Definition: The electrical work done by electrical appliances per unit time. Represented by P.

3. Formula: P=W/t=UI

4. Unit (1) International unit: W

(2) Commonly used units: KW.

1KW=1000W

2. Factors affecting the size of electric power:

(1) The size of the electrical power is related to the current passing through the bulb. When the voltages are equal, the greater the current, the greater the electrical power.

(2) The electrical power is related to the voltage at both ends of the bulb. When the currents are equal, the higher the voltage, the greater the electrical power.

Homework and preview:

Classwork, questions 1, 2, 3, and 4.

Tutorial (preview):

1. Know the rated power and actual power of electrical appliances.

2. How to measure the rated power of a small light bulb?

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For more information about the "Electric Energy and Electric Power Understanding Electric Power" PPT courseware, please click the Electric Energy and Electric Power PPT Understanding Electric Power PPT tab.

"Understanding Electric Power" Electric Energy and Electric Power PPT Courseware 3:

"Understanding Electric Power" Electric Energy and Electric Power PPT Courseware 3 1. Start by understanding the nameplate of electrical appliances Rated voltage 220V Rated frequency 50Hz Rated power 1000kW What does 22025 on the nameplate mean? Rated voltage refers to the voltage when electrical appliances or electrical instruments are working normally..

"Understanding Electric Power" Electric Energy and Electric Power PPT Courseware:

"Understanding Electric Power" Electric Energy and Electric Power PPT Courseware [Learning Objectives] 1. Understand electrical power with examples and know the units of electrical power. 2. Know the relationship between electric power, current and voltage, and be able to use the formula of electric power to perform simple calculations. 3. Experience research...

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Update Time: 2024-07-06

This template belongs to Physics courseware Guangdong and Shanghai Edition Ninth Grade Physics Volume 1 industry PPT template

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