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

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 in increased energy transfer.
Power is the rate at which energy is supplied or absorbed over time, measured in watts.
Power can also be expressed as the product of the instantaneous voltage and current across an element.
The sign of power depends on the current&#39;s direction and the polarity of the voltage.
According to the passive sign convention, when the current enters a circuit element at the positive terminal of the voltage and exits the negative terminal, the element absorbs power.
Conversely, if the current enters the negative terminal and exits the positive terminal, the element supplies power.
The total power supplied to the circuit must equal the total power absorbed, validating the energy conservation law.
For an element, the energy absorbed or supplied is the integral of instantaneous power.
If a cassette player draws steady current, then using battery&#39;s parameters and power-energy relation, the player&#39;s runtime is calculated.

power and energy

The power and energy delivered to an element are subjects of great significance in the field of electrical engineering. It is a well-known fact that a 100-watt light bulb emits more light than a 60-watt one. Therefore, power and energy calculations play a crucial role in the analysis of electrical circuits.
Power, defined as the time rate of expending or absorbing energy, is quantified in units called watts (W). The relation between power and energy is mathematically given as
<img alt="Static equilibrium diagram, force vectors &#931;Fx=0, lever analysis, mechanical advantage." src="/files/ftp_upload/15065/15065_PT_Equation_1.svg" style="text-align: center; height: 36px;" data-altupdatedat="1761830439000" data-alt="Equation1" />
where "p" represents the power in watts (W), "w" denotes the energy in joules (J), and "t" signifies the time in seconds (s).
The power associated with the current passing through an element within a circuit is the product of the voltage across that element and the current flowing through it. When the current enters the circuit element at the positive terminal of the voltage and exits at the negative terminal, it adheres to the passive convention. In this convention, the voltage propels a positive charge in the same direction as indicated by the current. Consequently, the power computed by multiplying the element voltage by the element current represents the power received by the element. This power is occasionally referred to as "the power absorbed by the element" or "the power dissipated by the element." Importantly, the power received by an element can assume either positive or negative values, contingent upon the actual values of the element's voltage and current.
On the other hand, when the passive convention is not adhered to, the current enters the circuit element at the negative terminal of the voltage and exits at the positive terminal. In this case, the voltage drives a positive charge in the direction opposite to that indicated by the current. Therefore, when the element voltage and current do not comply with the passive convention, the power computed by multiplying these values represents the power supplied by the element. Similar to received power, supplied power can also be positive or negative, depending on the specific values of the element's voltage and current.
The relationship between the power received by an element and the power supplied by that same element is expressed as
<img alt="Static equilibrium equation, power absorbed equals negative power supplied, concept illustration." src="/files/ftp_upload/15065/15065_PT_Equation_2.svg" style="text-align: center; height: 14px;" data-altupdatedat="1761830439000" data-alt="Equation2" />
When the element voltage and current align with the passive convention, the energy received by an element is given by
<img alt="Static equilibrium diagram, equations &#931;Fx=0, showing balance in mechanical system analysis." src="/files/ftp_upload/15065/15065_PT_Equation_3.svg" style="text-align: center; height: 64px;" data-altupdatedat="1761830439000" data-alt="Equation3" />
Energy is defined as the capacity to perform work and is expressed in joules (J).

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 ...

Education

JoVE Core

Electrical Engineering

Unit 1

Basics of Electric Circuits

KEY TERMS AND CONCEPTS

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

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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...

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...

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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,...

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Circuit Source Symbols and Controls

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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...

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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

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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

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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

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

HS-PS3-4

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

HS-PS3-5

Circuit Power, Absorption, and Supply

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