Download a presentation on the power of electric current. Electrical engineering and electronics Linear DC circuits. The end result will be the cost

Lesson topic:

Lesson topic:

Work and power electric current

1. What letter is used to denote electrical voltage?

• 1) I 2) U 3) R 4) q

2. What is the unit of measure for electrical resistance called?

• 1) Joule 2) Ampere 3) Ohm 4) Volt

3. What letter is used to denote the strength of the current?

• 1) A 2) I 3) V 4) R

4. Which of the following values ​​is the same for all series-connected conductors?

• 1) voltage 2) current 3) resistance 4) charge

5.Sila current in the conductor:

• 1) is directly proportional to the voltage at the ends of the conductor and its resistance
• 2) is inversely proportional to the voltage at the ends of the conductor and its resistance
• 3) is directly proportional to the voltage at the ends of the conductor and inversely proportional to its resistance
• 4) is directly proportional to the resistance of the conductor and inversely proportional to its resistance.

• 1. 2)
• 2. 3)
• 3. 2)
• 4. 2)
• 5. 3)

Work of electric current

To determine the work of an electric current in any section of the circuit, it is necessary to multiply the voltage at the ends of this section of the circuit by electric charge passing through it.

A=U*q

A - Work,

U - Voltage,

q - Electric charge.

The work of an electric current is proportional to the strength of the current, voltage and time of passage of the current.

A=I*U*t

A - Electric current work,

I - Current strength,

U - Voltage,

t - Current passing time

Work of electric current

Unit of Work: Joule (J)

1 Joule = 1 Volt * 1 Amp * 1 second

1 J = 1 V * 1A * 1s

Units of work in multiples of the Joule: hectojoule, kilojoule, megajoule.

Express in Joules the work equal to

Instruments needed to measure the work of the current in the circuit:

Voltmeter

Ammeter

Power

Power is numerically equal to the work done per unit time.

P - Power

Power

Power unit: Watt (W)

1 Watt = 1 Volt * 1 Amp

1W = 1V * 1A

Units of power in multiples of watts: hectowatt, kilowatt, megawatt.

Express in watts the power equal to:

How much work is done by the electric current in light bulb in 3 minutes. Calculate the power of the electric current.

Name

Letter designation

Unit

Electric charge

Basic Formula

Current strength

Definition

Voltage

Resistance

Work of electric current

Power

Reflection

Continue the sentence:

• Today in class I learned...

• Now I can …

• It was interesting…

• The knowledge gained in today's lesson will be useful ...

Physics lesson in 8th grade.

, teacher of physics, MOBU "Nikitinskaya secondary school"

Theme: M electric current power.

Lesson type:combined.

Lesson Objectives:to reveal the concept of the power of an electric current, to find out on what factors the power of an electric current depends, to reveal methods for determining power.

Tasks:

Educational:

Educational:

to consolidate the already existing knowledge on the topic "Electric current".

get to know the concepts

continue the formation of the ability to explain the processes in the electrical circuit.

formation of communicative qualities, culture of communication

formation of interest in the subject being studied

stimulation of curiosity, activity in the lesson

working capacity development

Developing:

development of cognitive interest

development of intellectual abilities

development of skills to highlight the main thing in the studied material

development of skills to generalize the studied facts and concepts

Forms of work:frontal, work in small groups, work in pairs, individual.

Means of education:

Textbook "Physics 8" A.V. Peryshkin

Collection of problems in physics for grades 7-9, A.V. Peryshkin,

Handouts (test sheets, practical tasks).

Sources of electric current.

Ammeters.

Voltmeters.

Electric light bulbs.

Connecting wires.

Presentation "Power of electric current".

Computer.

Illustrations on the topic.

Lesson plan:

Organizing time.

Express survey

staging learning objectives

Joint study of the problem

Designing a new mode of action.

Transition to the stage of solving particular problems

Control at the end stage learning topic

Homework.

Pedagogical technologies and teaching methods: ICT technology, research, problem-based teaching methods, elements of student-centered learning, differentiated learning

Used Books:

Peryshkin A.V. textbook "Physics 8"

Lukashk "Collection of problems in physics grades 7 - 9", Moscow, "Drofa", 2008

V.A. Orlov "Thematic tests in physics grades 7 - 8", Moscow, "Verbum - M", 2001

G.N. Stepanova, A.P. Stepanov "Collection of questions and tasks in physics grades 5 - 9", St. Petersburg, "Valery SPD", 2001

1 slide

2 slide

WORK OF ELECTRIC CURRENT The work of electric current shows how much work has been done electric field when moving charges along a conductor. The work of an electric current is equal to the product of the current strength and the voltage and the time the current flows in the circuit. The unit of measurement of the work of electric current in the SI system: [ A ] \u003d 1 J \u003d 1A B c

3 slide

POWER OF ELECTRIC CURRENT The power of electric current shows the work done by the current per unit of time and is equal to the ratio of the work done to the time during which this work was done. (power in mechanics is usually denoted by the letter N, in electrical engineering - by the letter P) since A \u003d IUt, the power of the electric current is: The unit of power of the electric current in the SI system: [P] \u003d 1 W (watt) \u003d 1 A. B

4 slide

LEARN, GO! When calculating the work of an electric current, an off-system multiple unit of electric current work is often used: 1 kWh (kilowatt-hour). 1 kWh = ............. W.s = 3,600,000 J which show the work of an electric current completed over a certain period of time when various household electrical appliances. These meters show the work of electric current (electricity consumption) in "kWh". 1 kWh of energy allows you to smelt 20 tons of pig iron

5 slide

WOW, INTERESTING At one time, J. Watt proposed such a unit as "horsepower" as a unit of power. This unit of measurement has survived to this day. But in England in 1882, the British Association of Engineers decided to assign the name of J. Watt to the unit of power. Now the name of James Watt can be read on any light bulb. This was the first case in the history of technology of assigning own name unit of measure. From this case, the tradition of assigning proper names to units of measurement began.

6 slide

They say that ... one of Watt's steam engines was bought by a brewer to replace the horse that powered the water pump. When choosing required power of the steam engine, the brewer defined the horse's labor force as eight hours of non-stop work until the horse was completely exhausted. The calculation showed that every second the horse lifted 75 kg of water to a height of 1 meter, which was taken as a unit of power of 1 horsepower.

7 slide

EVERYONE RUN TO THE TASKS! Two electric lamps, whose power is 40 and 100 W, are designed for the same voltage. Compare the filament resistances of both lamps. The room is lit with 40 electric lamps from a flashlight, connected in series and fed from the city network. After one lamp burned out, the remaining 39 were again connected in series and plugged into the network. When was the room brighter: with 40 or 39 lights? Connected in series copper and iron wires of the same length and section are connected to the battery. Which one will stand out large quantity heat for same time?

8 slide

Solve the problem In a circuit with a voltage of 125 V, an electric lamp is turned on, the current in which is 0.4 A. Find the current power in the lamp. (Calculate the work of the current in 10 minutes)