Name: voltage
Uploaded: 2024-04-11T12:48:28.000Z
Duration: 1 min 13 s
Channel: JoVE

K12 Standards

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

9-12

Physical Science

Energy And Waves

Electricity

Voltage

The movement of electrons in a conductor requires some form of energy or work, usually provided by an external force, like a battery. This force is called the electromotive force or voltage.
Voltage signifies the energy required to transport a unit charge between two points. It is also referred to as potential difference and is measured in volts.
The plus and minus signs define the direction or polarity of the voltage.
There are two ways to perceive voltage: the potential at point a can be described as Vab volts higher than the potential at point b, or the potential at point a relative to point b is Vab.
Additionally, the voltage drop from a to b is equivalent to a voltage rise from b to a.
Voltage can be either constant or time-varying. A constant voltage, usually produced by a battery, is called a DC voltage. It is utilized in portable equipment powered by batteries.
A sinusoidally time-varying voltage produced by electric generators, is an AC voltage. It is supplied to houses for operating appliances.

voltage

The movement of electrons in a conductor requires some form of energy or work, usually provided by an external force, like a battery. This force is called the electromotive force or voltage. The voltage between two points, referred to as points "a" and "b," in an electric circuit is the energy (or work) needed to move a unit charge from point "a" to point "b," and this relationship is expressed mathematically as
<img alt="Static equilibrium equation; &#931;Fx=0; diagram illustrating force balance; physics concept." src="/files/ftp_upload/15064/15064_PT_Equation_1.svg" style="text-align: center; height: 38px;" data-altupdatedat="1761830439000" data-alt="Equation1" />
In this equation, "w" represents the energy measured in joules (J), and "q" represents the charge measured in coulombs (C). The voltage, denoted as "vab" is measured in volts (V).
Voltage, often referred to as the potential difference, signifies the energy required to move a unit charge through an element within the circuit. It is important to note that the value of a voltage can be either positive or negative, with its direction determined by its polarities, indicated as (+) and (-). In electrical terminology, it is customary to state that a voltage exists across an element. The notation "vab" represents the voltage between points "a" and "b" and can be interpreted in two distinct ways:
<ul>
	<li>&#8226; Point "a" is at a potential of "vab" volts higher than point "b."</li>
	<li>&#8226; The potential at point "a" with respect to point "b" is "vab" volts.</li>
</ul>
A constant voltage is categorized as a direct current (DC) voltage, typically represented as "V." DC voltages are commonly generated by sources such as batteries. On the other hand, a voltage that varies sinusoidally with time is called an alternating current (AC) voltage, represented as "v." AC voltages are typically produced by electric generators.

The movement of electrons in a conductor requires some form of energy or work, usually provided by an external force, like a battery. This force is called ...

Education

JoVE Core

Electrical Engineering

Unit 1

Basics of Electric Circuits

KEY TERMS AND CONCEPTS

charge and current

Charge and Current

Charge, an inherent property of matter, is responsible for a wide range of electric phenomena. The SI unit of charge is the coulomb.
All matter comprises ...

power and energy

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 ...

electric circuit elements

Electric Circuit Elements

Circuit elements are the basic building blocks of an electric circuit. They can be categorized as active and passive elements.
Active elements can ...

circuit terminology

Circuit Terminology

An electrical network is a system of interconnected elements, not necessarily forming a closed path.
In contrast, a circuit, also an interconnected ...

independent and dependent sources

Independent and Dependent Sources

Sources in a circuit can be independent or dependent.
Independent voltage or current sources supply voltage and current unaffected by other circuit ...

ohm's law

Ohm's Law

Resistors, often made from metallic alloys or carbon compounds, model a material&#39;s current-resisting behavior.
Ohm&#39;s law states that the voltage ...

kirchhoff's current law

Kirchhoff's Current Law

Kirchhoff&#39;s current law, or KCL, is based on the law of charge conservation. It states that the total current entering and leaving a node in a circuit ...

kirchhoff's voltage law

Kirchhoff's Voltage Law

Kirchhoff&#39;s voltage law, or KVL, is based on the principle of energy conservation.
It states that the algebraic sum of all voltages around a closed ...

voltage dividers

Voltage Dividers

In a series connection, resistors are sequentially linked, and the same current must flow through each.
The voltage across these resistors can be ...

current dividers

Current Dividers

In a parallel connection, resistors are connected between the same pair of nodes, creating an equal voltage across each.
Considering the schematic circuit ...

equivalent resistance

Equivalent Resistance

In circuit analysis, situations often arise where resistors are neither in series nor parallel configurations. To tackle such scenarios, three-terminal ...

design example: resistive touchscreen

Design Example: Resistive Touchscreen

A device engineer is tasked with designing a resistive touchscreen interface for a mobile device. It consists of two conductive layers: a flexible upper ...

key terms and concepts

Learn how voltage moves charge in electric circuits, how to read v_ab, and the difference between DC and AC voltage in high school physics.

Voltage in Electric Circuits | 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

High School

HS+Phy.P4

HS+Phy.P4U1.8

Texas Essential Knowledge and Skills

Physics

PHYS.6

PHYS.6.E

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

South Carolina College and Career Ready Science Standards

motion-and-stability-forces-and-interactions

Motion and Stability: Forces and Interactions

P-PS2-5

Georgia Standards of Excellence

SPS10.

Understanding Electrical Quantities

SP5.

Ohm’s Law

Energy

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 ...

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 ...

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 ...

Elastic Potential Energy

Elastic potential energy is the energy stored as a result of the deformation of an elastic object, such as the stretching of a spring. An object is ...

Conservation of Mechanical Energy

The mechanical energy E of a system is the sum of its potential energy U and the kinetic energy K of the objects within it. What happens to this ...

/files/media/science-education/science-education-thumbs/14702.jpg

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 ...

• Quantifying kinetic energy 
• Quantifying gravitational potential energy

Content elaboration: Energy content learned in middle school, specifically conservation of energy and the basic differences between kinetic and potential energy, is elaborated on and quantified in this course. Energy has no direction and has units of joules (J). Kinetic energy, Ek, can be mathematically represented by $E_{k}=\frac{1}{2}mv^{2}$. Gravitational potential energy, $E_{g}$, can be mathematically represented by $E_{g}=mgh$. The amount of gravitational potential energy of an object is measured relative to a reference that is considered to be at a point of zero energy. The reference may be changed to help understand different situations. Only the change in the amount of energy can be measured absolutely. The conservation of energy and equations for kinetic and gravitational potential energy can be used to calculate values associated with energy (e.g., height, mass, speed) for situations involving energy transfer and transformation. Opportunities to quantify energy from data collected in experimental situations (e.g., a swinging pendulum, a car traveling down an incline) should be provided.

Conservation of energy

Mechanisms of Heat Transfer I

Just as interesting as the effects of heat transfer on a system are the methods by which the heat transfer occur. Whenever there is a temperature ...

Mechanisms of Heat Transfer II

In convection, thermal energy is carried by the large-scale flow of matter. Ocean currents and large-scale atmospheric circulation, which result from the ...

conduction-convection-and-radiation-problem-solving

Conduction, Convection and Radiation: Problem Solving

There are three methods by which heat transfer can take place: conduction, convection, and radiation. Each method has unique and interesting ...

Work

Work is done when energy is transferred from one object to another. In other words, work is when a force acts on something that undergoes a displacement ...

Quantifying Heat

Thermal Energy&#160;

Microscopically, thermal energy is the kinetic energy associated with the random motion of atoms and molecules. Temperature is a ...

Quantifying Work

As a system undergoes a change, its internal energy can change, and energy can be transferred from the system to the surroundings, or from the ...

Transfer and transformation of energy (including work)

Content elaboration: In middle school, concepts of energy transfer and transformation were addressed. Topics included conservation of energy, conduction, convection and radiation, the transformation of electrical energy, and the dissipation of energy into thermal energy. Work was introduced as a method of energy transfer into or out of the system when an outside force moves an object over a distance. In this course, these concepts are further developed. As long as the force, F, and displacement, $\Delta x$ are in the same or opposite directions, work, W, can be calculated from the equation $W=F\Delta x$. Work can also be quantified as $W=\Delta E$. Energy transformations for a phenomenon can be represented through a series of pie graphs or bar graphs. Equations for work, kinetic energy and potential energy can be combined with the law of conservation of energy to solve problems; conceptual understanding of kinetic energy, potential energy and work should be emphasized. [cite: 218, 219] When energy is transferred from one system to another, some of the energy is transformed to thermal energy. Since thermal energy involves the random movement of many trillions of subatomic particles, it is less able to be organized to bring about further change. Therefore, even though the total amount of energy remains constant, less energy is available for doing useful work.

transfer-and-transformation-of-energy-including-work

Transfer and transformation of energy (including work)

Travelling Waves

A wave is a disturbance that propagates from its source, repeating itself periodically, and is typically associated with simple harmonic motion. ...

Wave Parameters

The simplest mechanical waves are associated with simple harmonic motion and repeat themselves for several cycles. These simple harmonic waves can be ...

Interference and Superposition of Waves

When two waves of the same nature occur in the same region simultaneously, they result in interference. Interference of waves implies that the net effect ...

Reflection of Waves

When a wave travels from one medium to another, it gets reflected at the boundary of the second medium. A common example of this is when a person yells at ...

Propagation of Waves

When a wave propagates from one medium to another, part of it may get reflected in the first medium, and part of it may get transmitted to the second ...

Sound Waves

Sound waves can be thought of as fluctuations in the pressure of a medium through which they propagate. Since the pressure also makes the medium&#39;s ...

Sound Waves: Interference

Sound waves can be modeled either as longitudinal waves, wherein the molecules of the medium oscillate around an equilibrium position, or as pressure ...

Interference: Path Lengths

Consider two sources of sound, that may or may not be in phase, emitting waves at a single frequency, and consider the frequencies to be the same.
Two ...

/files/media/science-education/science-education-thumbs/14727.jpg

Sound Waves: Resonance

Resonance is produced depending on the boundary conditions imposed on a wave. Resonance can be produced in a string under tension with symmetrical ...

Electromagnetic Waves

James Clerk Maxwell formulated a single theory combining all the electric and magnetic effects scientists knew during that time, calling the phenomena his ...

The Electromagnetic Spectrum

Electromagnetic waves are categorized according to their wavelengths and frequencies, giving the electromagnetic spectrum. These waves are classified as ...

propagation-speed-of-electromagnetic-waves

Propagation Speed of Electromagnetic Waves

Electromagnetic waves are consistent with Ampere&#39;s law. Assuming there is no conduction current Ampere&#39;s law is given as:


Consider a plane ...

Energy Carried By Electromagnetic Waves

Anyone who has used a microwave oven knows there is energy in electromagnetic waves. Sometimes, this energy is obvious, such as in the summer sun&#39;s ...

Doppler Effect - I

The Doppler effect and Doppler shift were named after the Austrian physicist and mathematician Christian Johann Doppler in 1842, who conducted experiments ...

Doppler Effect - II

The Doppler effect has several practical, real-world applications. For instance, meteorologists use Doppler radars to interpret weather events based on ...

• Refraction, reflection, diffraction, absorption, superposition
• Radiant energy and the electromagnetic spectrum
• Doppler shift

Content elaboration: As addressed in middle school, waves transmit energy from one place to another, can transfer energy between objects and can be described by their speed, wavelength, frequency and amplitude. These concepts were applied to seismic waves traveling through different materials. In elementary and middle school, reflection and refraction of light were introduced, as was absorption of radiant energy by transformation into thermal energy. In this course, these processes are conceptually addressed (not mathematically) from the perspective of waves and expanded to include other types of energy that travel in waves. When a wave encounters a new material, the new material may absorb the energy of the wave by transforming it to another form of energy, usually thermal energy. Waves can be reflected off solid barriers or refracted when a wave travels from one medium into another medium. Waves may undergo diffraction around small obstacles or openings. When two waves traveling through the same medium meet, they pass through each other and continue traveling through the medium as before. When the waves meet, they undergo superposition, demonstrating constructive and destructive interference. Sound travels in waves and undergoes reflection, refraction, interference and diffraction. In Physics, many of these wave phenomena will be studied further and quantified. Radiant energy travels in waves and does not require a medium. Sources of light energy (e.g., the sun, a light bulb) radiate energy continuously in all directions. Radiant energy has a wide range of frequencies, wavelengths and energies arranged into the electromagnetic spectrum. The electromagnetic spectrum is divided into bands that have different applications in everyday life: radio (lowest energy), microwaves, infrared, visible light, ultraviolet, X-rays and gamma rays (highest energy). Radiant energy of the entire electromagnetic spectrum travels at the same speed in a vacuum. Specific frequency, energy, or wavelength ranges of the electromagnetic spectrum are not required. However, the relative positions of the different bands, including the colors of visible light, are important (e.g., ultraviolet has more energy than microwaves). Total radiant energy depends on more than just the frequency. Radiant energy exhibits wave behaviors including reflection, refraction, absorption, superposition and diffraction. For opaque objects (e.g., paper, a chair, an apple), little if any radiant energy is transmitted into the new material. However, the radiant energy can be absorbed, usually increasing the thermal energy of the object and/or the radiant energy can be reflected. For rough objects, the reflection in all directions forms a diffuse reflection and for smooth shiny objects, reflections can result in clear images. Transparent materials transmit most of the energy through the material, but smaller amounts of energy may be absorbed or reflected. Changes in the observed frequency and wavelength of a wave can occur if the wave source and the observer are moving relative to each other. When the source and the observer are moving toward each other, the wavelength is shorter and the observed frequency is higher; when the source and the observer are moving away from each other, the wavelength is longer and the observed frequency is lower. [cite: 253, 254] This phenomenon is called the Doppler shift and can be illustrated by listening to an ambulance siren as it travels past. As discussed in the Universe section of this course, this phenomenon is important to current understanding of how the universe is expanding. As a result, the light we receive from distant galaxies has a noticeable shift toward redder wavelengths (the so-called "redshift"). Calculations to measure the apparent change in frequency or wavelength are not appropriate for this course.

Waves

Energy Basics

Chemical reactions, such as those that occur when you light a match, involve changes in energy as well as matter.

Chemical changes and their accompanying ...

Absorption of Radiation

The rate of heat transfer by emitted radiation is described by the Stefan-Boltzmann law of radiation:

where &#963; is the Stefan-Boltzmann constant, a ...

Phase Transitions

Whether solid, liquid, or gas, a substance&#39;s state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the ...

Heating and Cooling Curves

When a substance&#8212;isolated from its environment&#8212;is subjected to heat changes, corresponding changes in temperature and phase of the substance ...

Phase Diagrams

A phase diagram combines plots of pressure versus temperature for the liquid-gas, solid-liquid, and solid-gas phase-transition equilibria of a substance. ...

Conductors and Insulators

Some materials may easily let electrical charges pass through them, while others obstruct their flow. The former are called conductors and the latter ...

Temperature and Thermal Equilibrium

Heat and temperature are essential concepts for everyone every day. The study of heat and temperature is part of an area of physics known as ...

Content elaboration: In middle school, thermal energy is introduced as the energy of movement of the particles that make up matter. Processes of heat transfer, including conduction, convection and radiation, were studied. In other sections of this course, the role of thermal energy during heating, cooling and phase changes is explored conceptually and graphically. In this course, rates of thermal energy transfer and thermal equilibrium are introduced. Thermal conductivity depends on the rate at which thermal energy is transferred from one end of a material to another. Thermal conductors have a high rate of thermal energy transfer and thermal insulators have a slow rate of thermal energy transfer. The rate at which thermal radiation is absorbed or emitted by a system depends on its temperature, color, texture and exposed surface area. All other things being equal, in a given amount of time, black rough surfaces absorb more thermal energy than smooth white surfaces. An object or system is continuously absorbing and emitting thermal radiation. If the object or system absorbs more thermal energy than it emits and there is no change in phase, the temperature increases. If the object or system emits more thermal energy than is absorbed and there is no change in phase, the temperature decreases. For an object or system in thermal equilibrium, the amount of thermal energy absorbed is equal to the amount of thermal energy emitted; therefore, the temperature remains constant. [cite: 271, 272] In Chemistry, changes in thermal energy will be quantified for substances that change their temperature.

Thermal energy

Electrical Current

Electrical current is defined as the rate at which charge flows. When there is a large current present, such as that used to run a refrigerator, a large ...

Energy Transfer in Chemical Reactions

Chemical reactions require sufficient energy to cause the matter to collide with enough precision and force that old chemical bonds can be broken and new ...

Resistance

When a current moves through any conductor, the conductor causes some level of difficulty for the current to flow. The measure of that difficulty is known ...

Many materials exhibit a simple relationship between the values of current, voltage, and resistance, known as Ohm&#8217;s law. The current that flows ...

• Movement of electrons 
• Current 
• Electric potential (voltage) 
• Resistors and transfer of energy

Content elaboration: In earlier grades, concepts of electrical conductors and insulators were introduced. A complete loop is needed for an electrical circuit that may be in parallel or in series. In this course, current, voltage and resistance are introduced conceptually to explain what was observed in middle school. The differences between electrical conductors and insulators can be explained by how freely the electrons flow throughout the material due to how firmly electrons are held by the nucleus. By convention, electric current is the rate at which positive charge flows in a circuit. In reality, it is the negatively charged electrons that are actually moving. Current is measured in amperes (A). An ampere is equal to one coulomb of charge per second $(C/s)$. In an electric circuit, the power source supplies the electrons already in the circuit with electric potential energy by doing work to separate opposite charges. For a battery, the energy is provided by a chemical reaction that separates charges on the positive and negative sides of the battery. This separation of charge is what causes the electrons to flow in the circuit. These electrons then transfer energy to other objects and transform electrical energy into other forms (e.g., light, sound, heat) in the resistors. Current continues to flow even after the electrons transfer their energy. Resistors oppose the rate of charge flow in the circuit. The potential difference or voltage across an energy source is a measure of potential energy in joules supplied to each coulomb of charge. The volt (V) is the unit of potential difference and is equal to one joule of energy per coulomb of charge $(J/C)$. Potential difference across the circuit is a property of the energy source and does not depend upon the devices in the circuit. These concepts can be used to explain why current will increase as the potential difference increases and as the resistance decreases. Experiments, investigations and testing (3-D or virtual) are used to construct a variety of circuits and to measure and compare the potential difference (voltage) and current. Circuits are dealt with conceptually in this course. Calculations are reserved for Physics.

Voltage

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