"Joule's Law" Electric Power PPT Courseware 5

Description

"Joule's Law" Electric Power PPT Courseware 5

Review knowledge:

The work done by ________ is called electrical work, represented by letters. The process of current doing work is the process of converting energy into ________ energy (internal energy, light energy, mechanical energy). The formula for calculating electrical power: W = _____ = _____ = _____ = _____ = _____, the international unit of electrical power: _____, 1 joule = _____, "_____" ( ) is also commonly used in life as the unit of electrical power, 1KW.h = _____J.

Feedback 1:

When an electric current passes through a conductor, the conductor produces a _____ phenomenon, which is called the heating effect of the electric current. In this process, electrical energy is converted into _____ energy.

The heat generated by current flowing through a conductor may be related to the current flowing through the conductor, the resistance of the flow through the conductor, the voltage across it, and the time the current is energized.

A quantity is related to multiple factors. We often use the control variable method to study

Students designed and studied circuit diagrams and plans based on the relationship between electrical power and current, voltage, and time.

In conclusion

Conclusion 1: When the current and energization time are the same, the greater the resistance, the more heat generated by the current.

Conclusion 2: When the resistance and energization time are the same, the greater the current, the more heat the current generates.

Conclusion 3: When the resistance and current are the same, the longer the power-on time, the more heat the current generates.

From the above conclusion, it can be seen that the heat generated by an energized conductor is related to the resistance of the conductor, the current passing through the conductor, and of course the energization time.

Feedback 2: Review questions on the exploration process:

Example: The following is a record of the experimental process of the relationship between heat and resistance generated by current that Xiaoyu studied in the laboratory. If there are any incomplete parts, please help him fill them in.

Topic: Study the relationship between heat generated by current and resistance

Device and principle: Students in our group assembled the experimental device as shown in the picture. Two identical flasks were filled with kerosene, and a resistance wire was placed in each bottle. The resistance of the resistance wire in bottle A was greater than that of the resistance wire in bottle B. big. After the current is energized, the current passes through the resistance wire to generate heat, which causes the temperature of the kerosene to ____ and the volume to expand. The kerosene in the glass tube ____ (fill in "rise" or "fall"). The more heat generated by the electric current, the ____ height the kerosene will rise.

Experimental process: Turn on the circuit for a period of time and compare which of the two bottles of kerosene rises higher. The result of the experiment is: ____The kerosene in the bottle rises higher. This shows that the greater the resistance, the more heat is generated.

We conducted an inductive analysis of the experimental phenomena together and found the relationship between the amount of heat generated by the current and ____.

Feedback 3:

The heat generated by current passing through a conductor is proportional to ________, proportional to the ____ of the conductor, and proportional to the energized ____. This law is called ____. The mathematical expression is: Q=____. The current does work through the conductor. , if all electrical energy is converted into internal energy: Q W=____=____=____=____. In a series circuit, I is constant. The larger R is, the more heat is generated per unit time. In a parallel circuit, U is constant. The smaller R is, the larger I is (I is a squared increase) and the more heat is generated per unit time.

Class exercises:

1. A 10Ω resistor has a current of 1A. How much heat does it generate when it is powered for 10 seconds?

2. How much heat does a "220V 100W" soldering iron generate per minute when used at rated voltage?

Compliance testing

1. Review experiments and investigations: (please fill in the blanks in the following experimental report)

Explore the heating effects of electric current:

process:

The resistance of resistance wires A and B is R A < R B. When the switch is closed for a period of time, it is found that the thermometer of bottle A indicates the reading of the thermometer of bottle B.

in conclusion:

The experiment shows that when _____ and the power-on time are the same, the greater the resistance of the conductor, the greater the heat generated by the current.

Application method:

In the experiment, electrical energy is converted into _____ energy. Excessive electric heat can easily cause fire, but it can be controlled and utilized to make an electric heater. The scientific method used here is the _____ method.

Knowledge expansion

1. What are the differences and connections between concepts such as electric work and electric energy, electric work and electric power, electric work and electric heat.

2. Why does the wire burn out and the power supply burn out when the circuit is short-circuited? After learning Joule's law, do you know the reason?

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For more information about the "Electrical Power Joule's Law" PPT courseware, please click the Electric Power ppt Joule's Law ppt tag.

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Update Time: 2024-10-06

This template belongs to Physics courseware Lu Jiao Edition Ninth Grade Physics Volume 1 industry PPT template

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