Name: circuit power, absorption, and supply
Uploaded: 2024-04-11T12:48:28.000Z
Duration: 1 min 12 s
Channel: JoVE

K12 Standards

new-jersey-student-learning-standards-for-science

New Jersey Student Learning Standards for Science

High School

Physical Science

Energy

HS-PS3-1

Power and Energy

Энергия — это общая работа, необходимая для проведения тока по цепи.
Повышение напряжения приводит к увеличению объема выполняемой работы, пропусканию большего тока, что приводит к увеличению передачи энергии.
Мощность — это скорость, с которой энергия подается или поглощается с течением времени, измеряемая в ваттах.
Мощность также может быть выражена как произведение мгновенного напряжения и тока на элементе.
Знак мощности зависит от направления тока и полярности напряжения.
Согласно соглашению о пассивных знаках, когда ток поступает на элемент цепи на положительной клемме напряжения и выходит из отрицательной клеммы, элемент поглощает энергию.
И наоборот, если ток поступает на отрицательную клемму и выходит из положительной клеммы, элемент подает питание.
Общая мощность, подаваемая в цепь, должна быть равна общей потребляемой мощности, что подтверждает закон сохранения энергии.
Для элемента поглощенная или подаваемая энергия является интегралом мгновенной мощности.
Если кассетный проигрыватель потребляет постоянный ток, то по параметрам батареи и соотношению мощности и энергии рассчитывается время работы плеера.

Сила и энергия

Мощность и энергия, передаваемая элементу, имеют большое значение в электротехнике. Общеизвестный факт: лампочка мощностью 100 Вт излучает больше света, чем лампочка мощностью 60 Вт. Поэтому расчеты мощности и энергии играют решающую роль при анализе электрических цепей.

Мощность, определяемая как скорость расходования или поглощения энергии во времени, измеряется в единицах, называемых ваттами (Вт). Соотношение между мощностью и энергией математически задается как

<img alt="Equation1" src="/files/ftp_upload/15065/15065_PT_Equation_1.svg" style="text-align: center; height: 36px;" />

где «p» представляет мощность в ваттах (Вт), «w» обозначает энергию в джоулях (Дж), а «t» означает время в секундах (с).

Мощность, связанная с током, проходящим через элемент внутри цепи, является произведением напряжения на этом элементе и тока, протекающего через него. Когда ток входит в элемент схемы на положительной клемме напряжения и выходит на отрицательной клемме, он подчиняется некоторому пассивному соглашению. Согласно ему, напряжение перемещает положительный заряд в том же направлении, что и ток. Следовательно, мощность, вычисленная путем умножения напряжения элемента на ток элемента, представляет собой мощность, полученную элементом. Эту мощность иногда называют «мощностью, поглощаемой элементом» или «мощностью, рассеиваемой элементом». Важно отметить, что мощность, получаемая элементом, может принимать как положительные, так и отрицательные значения в зависимости от фактических значений напряжения и тока элемента.

С другой стороны, когда пассивное соглашение не соблюдается, ток входит в элемент схемы на отрицательной клемме напряжения и выходит на положительной клемме. В этом случае напряжение перемещает положительный заряд в направлении, противоположном направлению тока. Следовательно, когда напряжение и ток элемента не соответствуют пассивному соглашению, мощность, вычисленная путем умножения этих значений, представляет собой мощность, передаваемую элементом. Подобно получаемой мощности, передаваемая мощность также может быть положительной или отрицательной, в зависимости от конкретных значений напряжения и тока элемента.

Связь между мощностью, получаемой элементом, и мощностью, передаваемой этим же элементом, выражается как

<img alt="Equation2" src="/files/ftp_upload/15065/15065_PT_Equation_2.svg" style="text-align: center; height: 14px;" />

Когда напряжение и ток элемента соответствуют пассивному соглашению, энергия, полученная элементом, определяется выражением

<img alt="Equation3" src="/files/ftp_upload/15065/15065_PT_Equation_3.svg" style="text-align: center; height: 64px;" />

Энергия определяется как способность совершать работу и выражается в джоулях (Дж).

Энергия — это общая работа, необходимая для проведения тока по цепи.
Повышение напряжения приводит к тому, что выполняется больше работы, пропускается больше тока, что приводит к ...

Education

JoVE Core

Electrical Engineering

Электротехника

Unit 1

Раздел 1

Basics of Electric Circuits

Основы электрических цепей

KEY TERMS AND CONCEPTS

ОСНОВНЫЕ ТЕРМИНЫ И ПОНЯТИЯ

circuit power, absorption, and supply

Circuit power, absorption, and supply explain how much energy an element uses or delivers in an electric circuit. These ideas matter in electrical engineering because power and energy calculations help describe circuit behavior. A 100-watt light bulb, for example, emits more light than a 60-watt bulb, so wattage is a useful measure in real devices.

Power is the time rate of expending or absorbing energy. It is measured in watts, written as W. The relation between power and energy uses the variables p for power in watts, w for energy in joules, and t for time in seconds.

For a circuit element, power is found by multiplying the voltage across the element by the current through it. When current enters the positive terminal of the voltage and leaves the negative terminal, the passive convention is used. In this case, the voltage pushes positive charge in the same direction as the current.

Under the passive convention, the product of voltage and current gives the power received by the element. This is also called absorbed power or dissipated power. The received power can be positive or negative, depending on the actual voltage and current values.

If the current enters at the negative terminal and leaves at the positive terminal, the passive convention is not followed. Then the voltage drives positive charge opposite to the current direction. In that case, the product of voltage and current represents the power supplied by the element, and this supplied power can also be positive or negative.

The power received by an element and the power supplied by the same element are related. When voltage and current follow the passive convention, the energy received by the element is given by the power-energy relation over time. Energy is the capacity to perform work, and it is measured in joules, or J.

Circuit Power, Absorption, and Supply

charge and current

Electric Charge in Circuits

Electric charge in circuits explains how charged particles behave in matter and how current is produced. Everyday static effects, like a wool sweater sticking to the body or a shock from a carpet, show charge in action. Charge is an inherent property of atomic particles and is measured in coulombs (C). Matter is made of atoms with electrons, protons, and neutrons. Electrons carry a negative charge (-e), and protons carry a positive charge (+e). These two charges have the same magnitude. An...

voltage

Voltage in Electric Circuits

Voltage in electric circuits is the energy needed to move electric charge between two points. It is also called electromotive force, or EMF. In most circuits, an external force such as a battery provides this energy for electron movement in a conductor. The voltage between points a and b is written as v_ab. It is defined as the work, or energy, needed to move a unit charge from point a to point b. In the equation, w is the energy in joules and q is the charge in coulombs. Voltage is measured...

power and energy

Circuit power, absorption, and supply explain how much energy an element uses or delivers in an electric circuit. These ideas matter in electrical engineering because power and energy calculations help describe circuit behavior. A 100-watt light bulb, for example, emits more light than a 60-watt bulb, so wattage is a useful measure in real devices. Power is the time rate of expending or absorbing energy. It is measured in watts, written as W. The relation between power and energy uses the...

electric circuit elements

Circuit Elements: Passive, Active, and Linear

Circuit elements are the building blocks of an electric circuit. An electric circuit is the connection of these elements. In this context, circuit elements are often grouped by how they behave and whether they supply energy. One major group is passive elements. These elements do not generate energy. Common passive elements include resistors, capacitors, and inductors. The other group is active elements, which can generate energy. Generators, batteries, and operational amplifiers are typical...

circuit terminology

Circuit Parts: Branches, Nodes, and Loops

Circuit parts like branches, nodes, loops, and meshes help describe how electrical networks work. An electrical network is a system of connected elements, such as resistors, capacitors, inductors, and voltage or current sources. Unlike a circuit, a network does not have to form a closed path. A circuit is also made of connected electrical elements, but it must include one or more closed paths. These loops let current flow continuously, which is what makes the circuit operate. Because of this,...

independent and dependent sources

Circuit Source Symbols and Controls

Circuit sources in electrical circuits can be independent or dependent. They provide the power a circuit needs to operate. Independent voltage sources supply a fixed voltage, and independent current sources supply a fixed current. Their output does not change because of other parts in the circuit. These sources use standard symbols in circuit diagrams. An independent voltage source is shown with + and - signs to mark the potential difference. An independent current source is shown with an...

ohm's law

Resistance and Conductance in Circuits

Resistance and conductance help explain how electric current moves through a circuit. Resistors are basic circuit parts made from metallic alloys or carbon compounds. They are used to model how a material resists current and to control and regulate electrical power in a circuit. Ohm's law describes the link between voltage and current across a resistor. The voltage across a resistor is directly proportional to the current through it. The constant that sets this relationship is resistance.

kirchhoff's current law

Kirchhoff's Current Law at Circuit Nodes

Kirchhoff's Current Law explains how current behaves at a circuit node. A node is the point where two or more circuit elements meet. The law says the current entering a node equals the current leaving it. That balance follows the rule of charge conservation, which means electric charge is not lost at the junction. When applying KCL, currents entering the node are treated as positive and currents leaving the node are treated as negative. The currents can be added algebraically at the node, and...

kirchhoff's voltage law

Voltage Balance in Closed Circuit Loops

Kirchhoff's Voltage Law explains how voltage is balanced in a closed circuit loop. It is a basic rule in electrical engineering and comes from the idea of energy conservation. Energy can change form, but it cannot be created or destroyed. KVL states that the algebraic sum of all voltages around a closed path, or loop, is zero. In other words, the total voltage supplied in a loop equals the total voltage drop across the components in that loop. A loop can be traced clockwise or anticlockwise,...

voltage dividers

Series Resistors and Voltage Split

Series resistors split voltage across a circuit. In a series setup, resistors are linked one after another. The same current flows through each resistor in the chain. To analyze this behavior, Ohm's law is used to relate voltage, current, and resistance. Kirchhoff's voltage law says the voltages around a series loop add up to the source voltage. That means the current in the circuit equals the source voltage divided by the total resistance in series. The current value can then be used in Ohm's...

current dividers

Parallel Resistors and Current Division

Parallel resistors share the same two nodes, so each resistor has the same voltage across it. In this circuit setup, Kirchhoff's current law applies. The source current equals the sum of the currents through each branch. Ohm's law helps find the branch currents from the source voltage and the resistor values. The source current is equal to the source voltage times the sum of the reciprocals of the resistances. This makes it easier to calculate how current divides in the circuit. The current...

equivalent resistance

Delta-Wye Network Conversion

Delta-wye network conversion helps analyze resistor circuits that are not arranged in simple series or parallel paths. These three-terminal equivalent networks use the wye (Y), also called tee (T), and the delta (Δ), also called pi (π), as practical circuit models. These networks are useful in many circuit settings. They appear in three-phase electrical systems, electrical filters, and matching networks. They can also be used on their own or combined with more complex circuits. A delta...

design example: resistive touchscreen

Resistive Touchscreen Voltage Mapping

A resistive touchscreen uses voltage mapping to locate a finger touch on a mobile device. It is built from two metallic layers. The top layer is flexible, and the bottom layer is rigid. A narrow gap separates them, and the high resistance between the layers is an important part of the design. When a user touches the screen, the two layers meet at one point. That contact point is called the touchpoint. The touch lowers the resistance between the layers at that spot and changes the electrical...

key terms and concepts

Learn how voltage, current, and the passive convention determine circuit power, absorbed power, supplied power, and energy in joules for high school circuits.

Circuit Power, Absorption, and Supply | JoVE K12

JoVE Core Electrical Engineering offers easy-to-understand animated videos that cover fundamental concepts of electric circuits along with circuit analysis techniques. It incorporates first-order and second-order circuits using operational amplifiers and circuit transformation concepts. The inclusion of practical design examples and real-world applications through scientist-in-action videos adds significant educational value, making complex concepts accessible.

electrical engineering

Arizona Science Standards

HS+Phy.P4

HS+Phy.P4U2.7

HS+Phy.P4U1.8

HS.P4

HS.P4U3.9

south-carolina-college-and-career-ready-science-standards

South Carolina College and Career Ready Science Standards

Physics

motion-and-stability-forces-and-interactions

Motion and Stability: Forces and Interactions

P-PS2-5

Energy is the total work required to drive the current through the circuit.
A rise in voltage results in more work done, passing more current, resulting ...

Energy and Work

Source: Ketron Mitchell-Wynne, PhD,&#160;Asantha Cooray, PhD, Department of Physics &#38; Astronomy, School of Physical Sciences, University of ...

First Law of Thermodynamics

A change in the internal energy of a system depends on the the net heat transfer into the system and the net work done by the system. The first law of ...

first-law-of-thermodynamics-problem-solving

First Law Of Thermodynamics: Problem-Solving

The first law of thermodynamics states that the change in internal energy of the system is equal to the net heat transfer into the system minus the net ...

conservation-of-energy-approach-to-system-analysis

Conservation of Energy Approach to System Analysis

Source: Ricardo Mejia-Alvarez and Hussam Hikmat Jabbar, Department of Mechanical Engineering, Michigan State University, East Lansing, MI
The purpose of ...

Cyclic Processes And Isolated Systems

A thermodynamic system with zero heat exchange and work is an isolated system. For these systems, the internal energy remains constant.
In the case of a ...

Isothermal Processes

A thermodynamic process that occurs at constant temperature is called an isothermal process. Heat slowly flows into the system or out of the system to ...

Isochoric and Isobaric Processes

A thermodynamic process that occurs at constant volume is called an isochoric process. According to the first law of thermodynamics, heat supplied or ...

Create a computational model to calculate the change in the energy of one component in a system when the change in energy of the other component(s) and energy flows in and out of the system are known. 

Clarification statement: Emphasis is on explaining the meaning of mathematical expressions used in the model. 

Assessment Boundary: Assessment is limited to basic algebraic expressions or computations; to systems of two or three components; and to thermal energy, kinetic energy, and/or the energies in gravitational, magnetic, or electric fields.

The universe is composed of matter in different forms, and all forms of matter contain energy.&#160; The different forms of energy on Earth originate from ...

Gravitational Potential Energy

Potential energy is not just a property of each object, but also a property of the interactions between objects in a chosen system. For each type of ...

Energy Stored in Capacitors

A parallel plate capacitor connected to a battery develops a potential difference across its plates.
By integrating the equation relating voltage and ...

Types of Potential Energy

Potential energy is also known as energy at rest or stored energy. Common types of potential energy include the gravitational potential energy stored in ...

Types of Kinetic Energy

The amount of kinetic energy of an object depends on its mass and speed. Consider two balls of different masses rolling down an inclined plane at the same ...

Kinetic Energy - I

It&#8217;s plausible to suppose that the greater the velocity of a body, the greater effect it could have on other bodies. This does not depend on the ...

Kinetic Energy - II

The kinetic energy of a particle is one-half of the product of the particle&#8217;s mass and the square of its speed. Note that just as Newton&#8217;s ...

Work-energy Theorem

According to Newton&#x2019;s second law of motion, the sum of all the forces acting on a particle (net force) determines the rate of change in the ...

Develop and use models to illustrate that energy at the macroscopic scale can be accounted for as a combination of energy associated with the motions of particles (objects) and energy associated with the relative position of particles (objects). 

Clarification statement: Examples of phenomena at the macroscopic scale could include the conversion of kinetic energy to thermal energy, the energy stored due to position of an object above the earth, and the energy stored between two electrically-charged plates. Examples of models could include diagrams, drawings, descriptions, and computer simulations.

HS-PS3-2

Conservation of Energy

The terms &#39;conserved quantity&#39;&#160;and &#39;conservation law&#39;&#160;have specific scientific meanings in physics, which differ from the ...

Conservation of Energy: Application

When solving problems using the energy conservation law, the object (system) to be studied should first be identified. Often, in applications of energy ...

Electric Generator: Alternator

Electric generators induce an emf by rotating a coil in a magnetic field. A simple alternator is an AC generator that creates electrical energy that ...

Dye-sensitized Solar Cells

Source: Tamara M. Powers, Department of Chemistry, Texas A&#38;M University
Today&#39;s modern world requires the use of a large amount of energy. While ...

Design, build, and refine a device that works within given constraints to convert one form of energy into another form of energy. 

Clarification statement: Emphasis is on both qualitative and quantitative evaluations of devices. Examples of devices could include Rube Goldberg devices, wind turbines, solar cells, solar ovens, and generators. Examples of constraints could include use of renewable energy forms and efficiency. 

Assessment Boundary: Assessment for quantitative evaluations is limited to total output for a given input. Assessment is limited to devices constructed with materials provided to students.

HS-PS3-3

Heat Flow and Specific Heat

Heat is a type of energy transfer that is caused by a temperature difference, and it can change the temperature of an object. Since heat is a form of ...

Calorimetry

When objects at different temperatures are placed in contact with each other but isolated from everything else, they attain thermal equilibrium. A ...

statements-of-the-second-law-of-thermodynamics

Statements of the Second Law of Thermodynamics

The second law of thermodynamics can be stated in several different ways, and all of them can be shown to imply the others. The Clausius&#8217; statement ...

entropy-and-the-second-law-of-thermodynamics

Entropy and the Second Law of Thermodynamics

The second law of thermodynamics can be stated quantitatively using the concept of entropy. Entropy is the measure of disorder of the system.
The ...

Thermodynamic Systems

A thermodynamic system is a set of objects whose thermodynamic properties are of interest. The system is considered to be embedded in its surroundings or ...

Work Done During Volume Change

In mechanics, work is done on an object when the force acting on it displaces the object. In thermodynamics, work done on a system can be estimated when ...

Path Between Thermodynamics States

Consider the two thermodynamic processes involving an ideal gas that are represented by paths AC and ABC in Figure 1:

In the first process for path A to ...

Heat and Free Expansion

The work done by a thermodynamic system depends not only on the initial and final states but also on the intermediate states&#8212;that is, on the path. ...

Internal Energy

The internal energy of a thermodynamic system is the sum of the kinetic and potential energies of all the molecules or entities in the system. The kinetic ...

Plan and conduct an investigation to provide evidence that the transfer of thermal energy when two components of different temperature are combined within a closed system results in a more uniform energy distribution among the components in the system (second law of thermodynamics). 

Clarification statement: Emphasis is on analyzing data from student investigations and using mathematical thinking to describe the energy changes both quantitatively and conceptually. Examples of investigations could include mixing liquids at different initial temperatures or adding objects at different temperatures to water. 

Assessment Boundary: Assessment is limited to investigations based on materials and tools provided to students.

HS-PS3-4

Maxwell's Equation Of Electromagnetism

James Clerk Maxwell (1831&#x2013;1879) was one of the major contributors to physics in the nineteenth century. Although he died young, he made major ...

Magnetic Force

In addition to the electric forces between electric charges, moving electric charges exert magnetic forces on each other. A magnetic field is created by a ...

Magnetic Fields

Source: Yong P. Chen, PhD, Department of Physics &#38; Astronomy, College of Science, Purdue University, West Lafayette, IN
Magnetic fields can be ...

Electric Fields

Source: Yong P. Chen, PhD, Department of Physics &#38; Astronomy, College of Science, Purdue University, West Lafayette, IN
An electric field is generated ...

Electric Charge in a Magnetic Field

Source: Andrew Duffy, PhD, Department of Physics, Boston University, Boston, MA
This experiment duplicates J.J. Thomson's famous experiment at the end of ...

Electric Potential Energy

When an electric field accelerates a free positive charge q, it is given kinetic energy. The process is analogous to an object accelerated by a ...

Develop and use a model of two objects interacting through electric or magnetic fields to illustrate the forces between objects and the changes in energy of the objects due to the interaction. 

Clarification statement: Examples of models could include drawings, diagrams, and texts, such as drawings of what happens when two charges of opposite polarity are near each other. 

Assessment Boundary: Assessment is limited to systems containing two objects.

HS-PS3-5

Circuit Power, Absorption, and Supply

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