Name: cutting electric bills with efficient lighting
Uploaded: 2023-09-18T17:11:16.000Z
Duration: 1 min 10 s
Channel: JoVE

K12 Standards

Next Generation Science Standards

High School

Physical Science

motion-and-stability-forces-and-interactions

Motion and Stability: Forces and Interactions

HS-PS2-5

Electrical Energy

Energię elektryczną można zdefiniować jako energię spowodowaną ruchem elektronów z jednego punktu do drugiego.
Ilość energii elektrycznej można określić na podstawie mocy zużywanej przez urządzenie w określonym przedziale czasu.
Jednostką energii elektrycznej w układzie SI jest dżul lub watosekunda, podczas gdy jednostką handlową jest kilowatogodzina, znana również jako jednostka Rady Handlu.
Weźmy pod uwagę żarówkę o mocy 60 W i żarówkę LED o mocy 20 W, z których każda wytwarza równoważną ilość światła.
Określ oszczędności wynikające z wymiany żarówki na żarówkę LED działającą przez 4 godziny dziennie przez 365 dni, zakładając, że 12 centów za kilowatogodzinę to średnia stawka za energię pobierana przez firmę energetyczną.
Najpierw indywidualnie określ ilość energii elektrycznej zużywanej przez żarówkę i żarówkę LED.
Po drugie, pomnóż energię zużywaną przez pojedynczą żarówkę przez koszt naliczany przez firmę energetyczną.
Żarówka LED zużywa trzy razy mniej energii i pozwala zaoszczędzić około 7,00 USD w porównaniu z żarówką.

<ol>
	<li>Protokół OpenStax. (2019). Fizyka uniwersytecka Vol. 2. [Wersja internetowa], str. 396 - 398. Źródło: <a href="https://openstax.org/books/university-physics-volume-2/pages/9-5-electrical-energy-and-power">https://openstax.org/books/university-physics-volume-2/pages/9-5-electrical-energy-and-power</a></li>
</ol>

energia elektryczna

Korzystanie z urządzeń elektrycznych przez dłuższy czas powoduje zużycie większej ilości energii elektrycznej i skutkuje wyższymi rachunkami za prąd. Energia wytwarzana w wyniku przeniesienia elektronów z jednego punktu do drugiego nazywana jest energią elektryczną. Jeśli moc jest dostarczana ze stałą szybkością, energię elektryczną można zdefiniować jako iloczyn mocy zużywanej przez urządzenie przez pewien okres czasu. Jednostką energii w rachunkach za energię elektryczną jest kilowatogodzina, gdzie jedna kilowatogodzina odpowiada 3,6''. 106 dżuli. Zużycie energii elektrycznej (E) można zmniejszyć poprzez skrócenie czasu użytkowania lub zmniejszenie zużycia energii przez to urządzenie lub osprzęt. To nie tylko zmniejsza koszty, ale także skutkuje mniejszym wpływem na środowisko.

Oświetlenie zużywa około 20% energii zużywanej w domach i blisko 40% w budynkach komercyjnych. Wydajność oświetlenia fluorescencyjnego jest około czterokrotnie większa niż w przypadku oświetlenia żarowego i dotyczy to zarówno długich świetlówek, jak i kompaktowych świetlówek. Przenikanie ciepła przez te świetlówki kompaktowe (CFL) jest mniejsze, a ich żywotność jest do 10 razy dłuższa niż w przypadku żarówek. Nowoczesne białe diody elektroluminescencyjne (LED), które składają się z szeregu maleńkich żarówek LED zgrupowanych razem, są jeszcze skuteczniejsze i działają pięć razy dłużej niż świetlówki kompaktowe.

Najprostszym sposobem na zmniejszenie zużycia energii w domach i budynkach komercyjnych jest przejście z żarówek na żarówki CFL lub LED. Żarówki CFL działają w oparciu o zupełnie inny mechanizm niż żarówki tradycyjne i zawierają pary argonu i rtęci umieszczone w spiralnej rurce. Używają „balastu” co zwiększa napięcie wykorzystywane przez żarówkę CFL. Statecznik wytwarza prąd elektryczny, który przepływa przez mieszaninę gazów i wzbudza cząsteczki gazu. Wzbudzone cząsteczki gazu wytwarzają światło ultrafioletowe (UV), które z kolei stymuluje powłokę fluorescencyjną po wewnętrznej stronie lampy. Powłoka ta fluoryzuje w zakresie widzialnym, emitując światło widzialne. Chociaż te żarówki zawierają rtęć, która jest trująca, rtęć nigdy nie zostanie uwolniona, dopóki żarówka nie pęknie. Nawet jeśli żarówka pęknie, rtęć ma tendencję do pozostawania w powłoce fluorescencyjnej. Jest to bardzo mała ilość, a korzyści wynikające z oszczędzania energii mogą przewyższać wady wynikające ze stosowania rtęci.

Energia elektryczna

Korzystanie z urządzeń elektrycznych przez dłuższy czas zużywa więcej energii elektrycznej i skutkuje wyższymi rachunkami za prąd. Energia wytwarzana przez ...

Education

JoVE Core

Physics

Fizyka

Unit 1

Jednostka 1

Current and Resistance

Natężenie prądu i rezystancja

KEY TERMS AND CONCEPTS

Kluczowe terminy i pojęcia

cutting electric bills with efficient lighting

Electrical energy is the energy transferred when electrons move from one point to another. The longer an appliance is used, the more electrical energy it consumes. If power stays constant, electrical energy equals the power used by the device times the time it runs. That is why longer use leads to a higher electric bill.

Electric bills measure this energy in kilowatt-hours. One kilowatt-hour is equal to 3.6 × 10^6 joules. You can lower electrical energy use by cutting the time an appliance runs or by choosing a device that uses less power. Both changes can lower cost and reduce environmental impact.

Lighting is a major part of energy use. It accounts for about 20% of the energy used at home and close to 40% in commercial buildings. Fluorescent lighting is about four times more efficient than incandescent lighting. This applies to both long fluorescent tubes and compact fluorescent lights, or CFLs.

CFLs give off less heat and last up to 10 times longer than incandescent bulbs. Modern white light-emitting diode, or LED, lights are even more effective. They are made of many tiny LED bulbs grouped together, and they can last five times as long as CFL bulbs. The easiest way to reduce energy use in homes and commercial buildings is to switch from incandescent bulbs to CFL or LED bulbs.

CFL bulbs work very differently from incandescent lights. They contain argon and mercury vapor inside a spiral-shaped tube. A ballast raises the voltage used by the CFL and creates an electric current. That current excites the gas molecules, which produce ultraviolet light. The UV light then makes the fluorescent coating on the inside of the tube glow in visible light.

CFL bulbs do contain mercury, which is poisonous, but it is not released as long as the bulb stays intact. Even if the bulb breaks, the mercury usually remains in the fluorescent coating. The amount is very small, and the energy saved may outweigh the drawback of using mercury.

Cutting Electric Bills with Efficient Lighting

cutting-electric-bills-with-efficient-lighting

electrical current

Current Flow in Simple Circuits

Electrical current is the flow of charge in a circuit. A large current means a large amount of charge moves through a wire in a short time. A small current means only a small amount of charge moves through the circuit over a longer time. Examples include the current needed to run a refrigerator and the smaller current used by a handheld calculator. The SI unit for current is the ampere, or amp. It is named for the French physicist André-Marie Ampère (1775–1836). One ampere means one coulomb of...

drift velocity

Electrical Current and Electron Drift

Electrical current in a conductor depends on moving charges and the tiny drift speed of those charges. When a free charge enters a wire, it pushes nearby charges ahead because like charges repel each other. That push spreads through the material very quickly, so the electrical signal moves through the system at nearly the speed of light. This fast signal is not the same as the slow motion of each charge. It is a rapidly spreading change in the electric field, often described as an electrical...

current density

Current Density in Wires and Solutions

Current density describes how much electric current passes through a given cross-sectional area. It helps show not just the size of the current, but also how it is distributed through a conductor. The current density can change from point to point because the local charge flow can vary. If the current flow is uniform, the amount of current is the same at every point along the conductor, even when the conductor’s area changes. Current density is measured in amperes per square meter. Its...

resistivity

Resistivity in Conductors and Insulators

Resistivity describes how much a material opposes electric current. When a voltage is applied to a conductor, an electric field forms. The charges in the conductor feel that force, and a current density develops. In some materials, including metals at a given temperature, the current density is approximately proportional to the electric field. In those cases, current density can be modeled with conductivity, written as sigma. Electrical conductivity is measured in (ohm·m)^−1. It tells how well...

resistance

Factors That Affect Electrical Resistance

Electrical resistance describes how much a conductor opposes the flow of current. It is represented by R. When current passes through a conductor, heat is also produced. Resistance is tied to the material’s resistivity, which is a property of the material used to make an electrical component. Resistance is different from resistivity. Resistivity belongs to the material itself, while resistance belongs to the finished component. To study this relationship, consider a wire with length L,...

ohm's law

Measuring Current, Voltage, and Resistance

Ohm's law describes the relationship between current, voltage, and resistance in many materials. In these cases, the current through a substance is directly proportional to the voltage applied to it. The idea was first shown experimentally by German physicist Georg Simon Ohm, who studied current in a metal wire. A material, component, or device that follows this pattern is called ohmic. An ohmic component has a current that increases in step with voltage. A material or component that does not...

non-ohmic devices

Diode Current and Reverse Bias

A diode is a nonohmic circuit element that makes current and voltage behave differently from Ohm’s law. In most substances, current is proportional to the voltage applied, but a diode does not show a linear current-voltage relationship. A diode is a semiconducting device with two terminals: an anode, which is the positive terminal, and a cathode, which is the negative terminal. It allows current to flow in only one direction. In a simple circuit with a battery, a diode, and a resistor, the...

electrical power

Power Limits in Electrical Circuits

Electrical power in a circuit depends on current and voltage. It is the product of these two values and is measured in watts, or joules per second. That relationship helps explain how much energy a circuit can deliver. A car’s auxiliary power outlet is one real-world example. Some outlets are rated at 20 amps and 12 volts, so they can deliver a maximum of 240 watts. That rating shows the upper limit of power the circuit can provide to devices such as a cell phone charger. Bulb wattage also...

electrical energy

Electrical energy is the energy transferred when electrons move from one point to another. The longer an appliance is used, the more electrical energy it consumes. If power stays constant, electrical energy equals the power used by the device times the time it runs. That is why longer use leads to a higher electric bill. Electric bills measure this energy in kilowatt-hours. One kilowatt-hour is equal to 3.6 × 10^6 joules. You can lower electrical energy use by cutting the time an appliance...

continuity equation

Charge Conservation and Current Flow

Charge conservation and current flow are linked through the continuity equation. The current density is the amount of current flowing per unit cross-sectional area. The current through a surface can be written as a surface integral of the current density. The conservation of charge says that the total current leaving a volume equals the rate at which charge inside that volume decreases. The total charge can be written using volume charge density, which is a space function. Because of this, the...

boundary conditions for current density

Current Density at Conductivity Boundaries

Current density at a boundary changes when two conducting materials have different electrical conductivities. The normal component of current density stays continuous across the interface. The tangential component, which runs along the surface, becomes discontinuous across the boundary. Consider two conducting media with conductivities σ1 and σ2 separated by an interface. At point P1 in medium 1, the steady current density makes an angle α1 with the normal. At point P2 in medium 2, the current...

electrical conductivity

Resistance and Ohm's Law in Conductors

Resistance and Ohm's law help explain how electric current moves through a conductor. In a perfect conductor, the electric field inside is zero because free electrons move to cancel it. Any extra charge then stays on the surface. In a practical conductor, an applied electric field can remain in place. That field drives electrons through the material and creates a current. The current density, which is current per unit area, is related to the electric field. More generally, it is related to the...

theory of metallic conduction

Electron Drift in Metallic Conduction

Electron drift in metallic conduction explains how free electrons move through a conductor. A classical model can describe this motion closely, even though quantum mechanics gives the best overall picture. This model is called the theory of metallic conduction. In this theory, Newton's second law is used to find the acceleration of an electron when an electric field is applied. The electron's velocity is then found from that acceleration. The electron travels through a crystal of positive ions...

key terms and concepts

Learn how electrical energy use affects electric bills and why CFL and LED bulbs can reduce power use, heat, and cost in homes and schools.

Cutting Electric Bills with Efficient Lighting | JoVE K12

physics

JoVE Core Physics introduces the theory and application of fundamental physics topics, including kinematics, dynamics, fluid mechanics, statics, waves, and acoustics, with concise and easy-to-understand animated videos. Additionally, the scientist-in-action videos demonstrate the application of related concepts in classical and original research experiments performed in today's laboratories worldwide.

Cutting Electric Bills with Efficient Lighting

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