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

Energia é o trabalho total necessário para conduzir a corrente através do circuito.
Um aumento na tensão resulta em mais trabalho realizado, passando mais corrente, resultando em maior transferência de energia.
Potência é a taxa na qual a energia é fornecida ou absorvida ao longo do tempo, medida em watts.
A potência também pode ser expressa como o produto da tensão e corrente instantâneas em um elemento.
O sinal de potência depende da direção da corrente e da polaridade da tensão.
De acordo com a convenção de sinal passivo, quando a corrente entra em um elemento do circuito no terminal positivo da tensão e sai do terminal negativo, o elemento absorve energia.
Por outro lado, se a corrente entrar no terminal negativo e sair do terminal positivo, o elemento fornecerá energia.
A potência total fornecida ao circuito deve ser igual à potência total absorvida, validando a lei de conservação de energia.
Para um elemento, a energia absorvida ou fornecida é a integral da potência instantânea.
Se um toca-fitas consome corrente constante, usando os parâmetros da bateria e a relação energia-energia, o tempo de execução do player é calculado.

poder e energia

A potência e a energia entregues a um elemento são assuntos de grande importância no campo da engenharia elétrica. É um fato bem conhecido que uma lâmpada de 100 watts emite mais luz do que uma de 60 watts. Portanto, os cálculos de potência e energia desempenham um papel crucial na análise de circuitos elétricos.

A potência, definida como a taxa de tempo de consumo ou absorção de energia, é quantificada em unidades chamadas watts (W). A relação entre potência e energia é matematicamente dada como:

<img alt="Equation1" src="/files/ftp_upload/15065/15065_PT_Equation_1.svg" style="text-align: center; height: 36px;" />

onde “p” representa a potência em watts (W), “w” denota a energia em joules (J) e “t” significa o tempo em segundos (s).

A potência associada à corrente que passa por um elemento dentro de um circuito é o produto da tensão nesse elemento e da corrente que flui através dele. Quando a corrente entra no elemento do circuito no terminal positivo da tensão e sai no terminal negativo, ela adere à convenção passiva. Nesta convenção, a tensão impulsiona uma carga positiva na mesma direção indicada pela corrente. Consequentemente, a potência calculada multiplicando a tensão do elemento pela corrente do elemento representa a potência recebida pelo elemento. Essa potência é ocasionalmente chamada de “a potência absorvida pelo elemento” ou “a potência dissipada pelo elemento”. É importante ressaltar que a potência recebida por um elemento pode assumir valores positivos ou negativos, dependendo dos valores reais da tensão e da corrente do elemento.

Por outro lado, quando a convenção passiva não é respeitada, a corrente entra no elemento do circuito no terminal negativo da tensão e sai no terminal positivo. Neste caso, a tensão aciona uma carga positiva no sentido oposto ao indicado pela corrente. Portanto, quando a tensão e a corrente do elemento não atendem à convenção passiva, a potência calculada pela multiplicação desses valores representa a potência fornecida pelo elemento. Semelhante à potência recebida, a potência fornecida também pode ser positiva ou negativa, dependendo dos valores específicos de tensão e corrente do elemento.

A relação entre a potência recebida por um elemento e a potência fornecida por esse mesmo elemento é expressa como:

<img alt="Equation2" src="/files/ftp_upload/15065/15065_PT_Equation_2.svg" style="text-align: center; height: 14px;" />

Quando a tensão e a corrente do elemento se alinham com a convenção passiva, a energia recebida por um elemento é dada por:

<img alt="Equation3" src="/files/ftp_upload/15065/15065_PT_Equation_3.svg" style="text-align: center; height: 64px;" />

A energia é definida como a capacidade de realizar trabalho e é expressa em joules (J).

Poder e Energia

Energia é o trabalho total necessário para conduzir a corrente através do circuito.
Um aumento na tensão resulta em mais trabalho realizado, passando mais corrente, resultando ...

Education

JoVE Core

Electrical Engineering

Engenharia Elétrica

Unit 1

Unidade 1

Basics of Electric Circuits

Fundamentos de Circuitos Elétricos

KEY TERMS AND CONCEPTS

TERMOS E CONCEITOS-CHAVE

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.
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First Law Of Thermodynamics: Problem-Solving

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Conservation of Energy Approach to System Analysis

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Isochoric and Isobaric Processes

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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.

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Gravitational Potential Energy

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Types of Kinetic Energy

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Kinetic Energy - I

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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

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Conservation of Energy: Application

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Dye-sensitized Solar Cells

Source: Tamara M. Powers, Department of Chemistry, Texas A&#38;M University
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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

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Calorimetry

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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 ...

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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.
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Thermodynamic Systems

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Internal Energy

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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

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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
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Electric Fields

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