Asked by: Carel Lucas, Perth, AustraliaDrift velocity, the average speed at which electrons travel in a conductor when subjected to an electric field, is about 1mm per second. It’s the electromagnetic wave rippling through the electrons that propagates at close to the speed of light. Read more:
- How exactly does electricity kill you?
- Why are water and electricity a deadly combination?
How fast does electricity travel down a wire?
I bought 1000 meters of wire to settle a physics debate
The individual electron velocity in a metal wire is typically millions of kilometers per hour. In contrast, the drift velocity is typically only a few meters per hour while the signal velocity is a hundred million to a trillion kilometers per hour.
Is electricity as fast as the speed of light?
) At the same time Brian is on earth and Janet is on Mars. Janet has a battery; Brian has a light bulb. Suppose a very long pair of wires goes from the + side of the battery on Mars all the way to the light bulb on Earth and back to the Janet’s hand on Mars.
She connects the wire to the side of the battery. How long does it take before Brian sees the light bulb turn on? MARS. EARTHJanet. Brianbattery + —————————————light battery — —————————————bulb Your question is: Does it take less time for Ismael to see the light, or for Brian to see the light? One of the principles of physics is that NOTHING goes faster than the speed of light in space.
Therefore it is impossible for Brian to see the light before Ismael. (Electricity is NOT faster than Light. ) However, is it possible for Ismael to see the light at the same time as Ismael? (In otherwords, Is Electricty AS FAST as Light?) The answer: ALMOST but NOT QUITE.
It is impossible for him to see it at a different time !» Just how fast the Electricity goes depends on the shape of the two wires going from Mars to Earth. WHY? Another principle of physics is that Light and Electricity are the SAME THING. Electricity is just Light guided along wires.
(Sort of. ) But this «guiding» of light along the wires makes it slow down little. In addition, the electrons flowing through the wires constantly bump into the atoms of the wire, which slows them down considerably.
If you were to take the electrons out of the wire and make them flow through space (which is essentially what you do when you make a spark), they can move faster, but no matter what, they cannot move as fast light.
A guy named Maxwell,a creative physicist,developed the theory and first understood the relation between electricity and light. He was a true giant of science and physics. Maxwell’s equations are fundamental to modern science and technology especially as it relates to electricity, electronics, lasers, radio waves, light etc.
Click Here to return to the search form.
Does anything travel faster than light?
—> Warp drive: could positive-energy solitons move a spacecraft faster than the speed of light? (Courtesy: iStock/VikaSuh) Albert Einstein’s special theory of relativity famously dictates that no known object can travel faster than the speed of light in vacuum, which is 299,792 km/s. This speed limit makes it unlikely that humans will ever be able to send spacecraft to explore beyond our local area of the Milky Way. However, new research by Erik Lentz at the University of Göttingen suggests a way beyond this limit. The catch is that his scheme requires vast amounts of energy and it may not be able to propel a spacecraft.
- Lentz proposes that conventional energy sources could be capable of arranging the structure of space–time in the form of a soliton – a robust singular wave
- This soliton would act like a «warp bubble'», contracting space in front of it and expanding space behind
Unlike objects within space–time, space–time itself can bend, expand or warp at any speed. Therefore, a spacecraft contained in a hyperfast bubble could arrive at its destination faster than light would in normal space without breaking any physical laws, even Einstein’s cosmic speed limit.
Does electricity actually flow?
November 2001 — To answer this question we need to look at matter itself at a most basic level. Matter is made up of small units called atoms. At this atomic level matter possesses two basic characteristics. Matter has mass and it may have an electrical charge, either positive, negative, or it could be neutral with no charge.
Each atom contains three types of particles with different characteristics; positive protons, neutral neutrons, and negative electrons. Electric current (electricity) is a flow or movement of electrical charge.
The electricity that is conducted through copper wires in your home consists of moving electrons. The protons and neutrons of the copper atoms do not move. The actual progression of the individual electrons in a given direction through the wire is quite slow.
The electrons have to work their way through the billions of atoms in the wire and this takes considerable time. In the case of a 12 gauge copper wire carrying 10 amperes of current (typical of home wiring), the individual electrons only move about 0.
02 cm per sec or 1. 2 inches per minute (in science this is called the drift velocity of the electrons. If this is the situation in nature, why do the lights come on so quickly? At this speed it would take the electrons hours to get to the lights. Atoms are very tiny, less than a billionth of a meter in diameter.
The wire is «full» of atoms and free electrons and the electrons move among the atoms. In a typical copper wire there would be trillions of electrons flowing past any given point in the wire every second, but they would be passing that point very slowly.
Think of the wire in comparison to a pipe full of marbles. If we push another marble into a filled pipe, then one marble would have to exit the other end. Electrons are like that in a wire. If one moves they all have to move. Thus when you turn on a switch an electrical potential difference (created by a generator) immediately causes a force that tries to move the electrons.
If you make one electron move when you turn on a switch, the electrons throughout the wire move, even if the wire is miles long. Therefore when you turn on a switch, the electrons in the light start moving «instantly» as far as we are concerned, i.
something starts to happen throughout the electrical system. Although the electrons are actually moving through the wire slowly, we say that the speed of electricity is near the speed of light (extremely fast). What we really mean is that the effects from the electricity occur «instantly.
Which is faster light or darkness?
Darkness travels at the speed of light. More accurately, darkness does not exist by itself as a unique physical entity, but is simply the absence of light. Any time you block out most of the light – for instance, by cupping your hands together – you get darkness.
How far can electricity travel in a wire?
Without it, life can get somewhat cumbersome. Power travels from the power plant to your house through an amazing system called the power distribution grid. In almost all cases, the power plant consists of a spinning electrical generator.
Something has to spin that generator — it might be a water wheel in a hydroelectric dam, a large diesel engine or a gas turbine. But in most cases, the thing spinning the generator is a steam turbine. The steam might be created by burning coal, oil or natural gas. Or the steam may come from a nuclear reactor like this one at the Shearon Harris nuclear power plant near Raleigh, North Carolina: No matter what it is that spins the generator, commercial electrical generators of any size generate what is called 3-phase AC power. To understand 3-phase AC power, it is helpful to understand single-phase power first. The Power Plant: Alternating Current Single-phase power is what you have in your house. You generally talk about household electrical service as single-phase, 120-volt AC service.
If you use an oscilloscope and look at the power found at a normal wall-plate outlet in your house, what you will find is that the power at the wall plate looks like a sine wave, and that wave oscillates between -170 volts and 170 volts (the peaks are indeed at 170 volts; it is the effective (rms) voltage that is 120 volts).
The rate of oscillation for the sine wave is 60 cycles per second. Oscillating power like this is generally referred to as AC, or alternating current. The alternative to AC is DC, or direct current. Batteries produce DC: A steady stream of electrons flows in one direction only, from the negative to the positive terminal of the battery. AC has at least three advantages over DC in a power distribution grid:
- Large electrical generators happen to generate AC naturally, so conversion to DC would involve an extra step.
- Transformers must have alternating current to operate, and we will see that the power distribution grid depends on transformers.
- It is easy to convert AC to DC but expensive to convert DC to AC, so if you were going to pick one or the other AC would be the better choice.
The power plant, therefore, produces AC. On the next page, you’ll learn about the AC power produced at the power plant. Most notably, it is produced in three phases. The Power Plant: Three-phase Power The power plant produces three different phases of AC power simultaneously, and the three phases are offset 120 degrees from each other. If you were to look at the three phases on a graph, they would look like this relative to ground: There is nothing magical about three-phase power. It is simply three single phases synchronized and offset by 120 degrees. Why three phases? Why not one or two or four? In 1-phase and 2-phase power, there are 120 moments per second when a sine wave is crossing zero volts. In 3-phase power, at any given moment one of the three phases is nearing a peak.
- There are four wires coming out of every power plant: the three phases plus a neutral or ground common to all three
- High-power 3-phase motors (used in industrial applications) and things like 3-phase welding equipment therefore have even power output
Four phases would not significantly improve things but would add a fourth wire, so 3-phase is the natural settling point. And what about this «ground,» as mentioned above? The power company essentially uses the earth as one of the wires in the power system.
- The earth is a pretty good conductor and it is huge, so it makes a good return path for electrons
- (Car manufacturers do something similar; they use the metal body of the car as one of the wires in the car’s electrical system and attach the negative pole of the battery to the car’s body
) «Ground» in the power distribution grid is literally «the ground» that’s all around you when you are walking outside. It is the dirt, rocks, groundwater, etc. , of the earth. Transmission Substation The three-phase power leaves the generator and enters a transmission substation at the power plant. A typical substation at a power plant You can see at the back several three-wire towers leaving the substation. Typical voltages for long distance transmission are in the range of 155,000 to 765,000 volts in order to reduce line losses. A typical maximum transmission distance is about 300 miles (483 km). High-voltage transmission lines are quite obvious when you see them. They are normally made of huge steel towers like this: All power towers like this have three wires for the three phases. Many towers, like the ones shown above, have extra wires running along the tops of the towers. These are ground wires and are there primarily in an attempt to attract lightning. The Distribution Grid For power to be useful in a home or business, it comes off the transmission grid and is stepped-down to the distribution grid.
This substation uses large transformers to convert the generator’s voltage (which is at the thousands of volts level) up to extremely high voltages for long-distance transmission on the transmission grid.
This may happen in several phases. The place where the conversion from «transmission» to «distribution» occurs is in a power substation. A power substation typically does two or three things:
- It has transformers that step transmission voltages (in the tens or hundreds of thousands of volts range) down to distribution voltages (typically less than 10,000 volts).
- It has a «bus» that can split the distribution power off in multiple directions.
- It often has circuit breakers and switches so that the substation can be disconnected from the transmission grid or separate distribution lines can be disconnected from the substation when necessary.
A typical small substation The box in the foreground is a large transformer. To its left (and out of the frame but shown in the next shot) are the incoming power from the transmission grid and a set of switches for the incoming power. Toward the right is a distribution bus plus three voltage regulators. The transmission lines entering the substation and passing through the switch tower The switch tower and the main transformer Now the distribution bus comes into the picture. Distribution Bus The power goes from the transformer to the distribution bus: In this case, the bus distributes power to two separate sets of distribution lines at two different voltages. The smaller transformers attached to the bus are stepping the power down to standard line voltage (usually 7,200 volts) for one set of lines, while power leaves in the other direction at the higher voltage of the main transformer. The power leaves this substation in two sets of three wires, each headed down the road in a different direction: The wires between these two poles are «guy wires» for support. They carry no current. The next time you are driving down the road, you can look at the power lines in a completely different light. In the typical scene pictured on the right, the three wires at the top of the poles are the three wires for the 3-phase power. The fourth wire lower on the poles is the ground wire. In some cases there will be additional wires, typically phone or cable TV lines riding on the same poles.
As mentioned above, this particular substation produces two different voltages. The wires at the higher voltage need to be stepped down again, which will often happen at another substation or in small transformers somewhere down the line.
For example, you will often see a large green box (perhaps 6 feet/1. 8 meters on a side) near the entrance to a subdivision. It is performing the step-down function for the subdivision. Regulator BankYou will also find regulator banks located along the line, either underground or in the air. A typical regulator bank Up toward the top are three switches that allow this regulator bank to be disconnected for maintenance when necessary: At this point, we have typical line voltage at something like 7,200 volts running through the neighborhood on three wires (with a fourth ground wire lower on the pole): Taps A house needs only one of the three phases, so typically you will see three wires running down a main road, and taps for one or two of the phases running off on side streets. Pictured below is a 3-phase to 2-phase tap, with the two phases running off to the right: Here is a 2-phase to 1-phase tap, with the single phase running out to the right: At the HouseAnd finally we are down to the wire that brings power to your house! Past a typical house runs a set of poles with one phase of power (at 7,200 volts) and a ground wire (although sometimes there will be two or three phases on the pole, depending on where the house is located in the distribution grid). At each house, there is a transformer drum attached to the pole, like this: In many suburban neighborhoods, the distribution lines are underground and there are green transformer boxes at every house or two. Here is some detail on what is going on at the pole: The transformer’s job is to reduce the 7,200 volts down to the 240 volts that makes up normal household electrical service. Let’s look at this pole one more time, from the bottom, to see what is going on: There are two things to notice in this picture:
- There is a bare wire running down the pole. This is a grounding wire. Every utility pole on the planet has one. If you ever watch the power company install a new pole, you will see that the end of that bare wire is stapled in a coil to the base of the pole and therefore is in direct contact with the earth, running 6 to 10 feet (1.
- There are two wires running out of the transformer and three wires running to the house. The two from the transformer are insulated, and the third one is bare. The bare wire is the ground wire. The two insulated wires each carry 120 volts, but they are 180 degrees out of phase so the difference between them is 240 volts. This arrangement allows a homeowner to use both 120-volt and 240-volt appliances. The transformer is wired in this sort of configuration:
The 240 volts enters your house through a typical watt-hour meter like this one: The meter lets the power company charge you for putting up all of these wires. Safety Devices: Fuses Fuses and circuit breakers are safety devices. Let’s say that you did not have fuses or circuit breakers in your house and something «went wrong. » What could possibly go wrong? Here are some examples:
- A fan motor burns out a bearing, seizes, overheats and melts, causing a direct connection between power and ground.
- A wire comes loose in a lamp and directly connects power to ground.
- A mouse chews through the insulation in a wire and directly connects power to ground.
- Someone accidentally vacuums up a lamp wire with the vacuum cleaner, cutting it in the process and directly connecting power to ground.
- A person is hanging a picture in the living room and the nail used for said picture happens to puncture a power line in the wall, directly connecting power to ground.
When a 120-volt power line connects directly to ground, its goal in life is to pump as much electricity as possible through the connection. Either the device or the wire in the wall will burst into flames in such a situation. (The wire in the wall will get hot like the element in an electric oven gets hot, which is to say very hot!). A fuse is a simple device designed to overheat and burn out extremely rapidly in such a situation.
They regulate the voltage on the line to prevent undervoltage and overvoltage conditions. 8 to 3 m) underground. It is a good, solid ground connection. If you examine a pole carefully, you will see that the ground wire running between poles (and often the guy wires) are attached to this direct connection to ground.
In a fuse, a thin piece of foil or wire quickly vaporizes when an overload of current runs through it. This kills the power to the wire immediately, protecting it from overheating. Fuses must be replaced each time they burn out. A circuit breaker uses the heat from an overload to trip a switch, and circuit breakers are therefore resettable. Safety Devices: Circuit Breakers Inside the circuit breaker panel (right) you can see the two primary wires from the transformer entering the main circuit breaker at the top. The main breaker lets you cut power to the entire panel when necessary. Within this overall setup, all of the wires for the different outlets and lights in the house each have a separate circuit breaker or fuse: If the circuit breaker is on, then power flows through the wire in the wall and makes its way eventually to its final destination, the outlet. What an unbelievable story! It took all of that equipment to get power from the power plant to the light in your bedroom. The next time you drive down the road and look at the power lines, or the next time you flip on a light, you’ll hopefully have a much better understanding of what is going on. The power distribution grid is truly an incredible system.
How fast is warp speed?
In the sci-fi universe of ‘Star Trek,’ spaceships with warp drives can zoom past the normally impenetrable limit of light speed, or about 186,282 miles per second (299,792 kilometers per second) in a vacuum.
Is warp speed possible?
Time Goes by So Slowly — «Comparatively» is the key. Alcubierre and later warp architects assumed an abrupt transition between the contorted spacetime in the wall of the bubble and the smooth interior and exterior. But Bobrick and Martire found this «truncation» of the gravitational field to be the reason why large amounts of negative energy are required to stabilize the contortion of space and time.
- Abandoning the cartoonish image of a soap bubble, however, makes it possible to build warp drives based on ordinary matter, they claim
- The gravitational field would not simply disappear when one moved away from the wall of the shell
Instead it would gradually decay. Spacetime would therefore also be curved inside the bubble. To travelers in a spaceship right in the middle of the bubble, this phenomenon would be most obvious in the passage of time: their watches would go slower than in the rest of space because, according to the theory of relativity, time is affected by gravity.
- The slower passage of time on a spaceship might be something interstellar travelers appreciate
- Still, Bobrick and Martire describe other obstacles
- So far, they argue, there is no known way to actually accelerate a warp bubble
All previous ideas about the subject simply assume that the curvature of spacetime is already moving at high speed. A beam of light travels 299,000 kilometers per second. According to Einstein’s special theory of relativity, this is a physical constant. The speed of light is the maximum speed any particle may reach, and a particle can only do so if it has no mass.
- Consequently, today’s physics offers no possibility of accelerating objects beyond the speed of light
- On closer inspection, however, this limit only applies within the four-dimensional spacetime comprising the universe
Outside of that, even greater speeds appear to be possible. «None of the physically conceivable warp drives can accelerate to speeds faster than light,» Bobrick says. That is because you would require matter capable of being ejected at speeds faster than light—but no known particles can travel that fast.
- Furthermore, the bubble could not be controlled by occupants of the spaceship itself because they would lose contact with the outside world, owing to the extremely strong curvature of space around them
Lentz sees these objections as a problem, too, but he believes a solution can be found. Bobrick, meanwhile, points out that it is also possible to travel to distant stars at a third or half the speed of light, especially if time passes more slowly for the people in the warp bubble.
Are Tachyons real?
Sign up for Scientific American’s free newsletters. » data-newsletterpromo_article-image=»https://static. scientificamerican. com/sciam/cache/file/4641809D-B8F1-41A3-9E5A87C21ADB2FD8_source. png» data-newsletterpromo_article-button-text=»Sign Up» data-newsletterpromo_article-button-link=»https://www.
- com/page/newsletter-sign-up/?origincode=2018_sciam_ArticlePromo_NewsletterSignUp» name=»articleBody» itemprop=»articleBody»> Raymond Y
- Chiao is professor of physics at the University of California, Berkeley
He replies:»Briefly, tachyons are theoretically postulated particles that travel faster than light and have ‘imaginary’ masses. Editor’s note: imaginary mass is a bizarre theoretical concept that comes from taking the square root of a negative number; in this case, it roughly means that a particle’s mass is only physically meaningful at speeds greater than light.
] «The name ‘tachyon’ (from the Greek ‘tachys,’ meaning swift) was coined by the late Gerald Feinberg of Columbia University. Tachyons have never been found in experiments as real particles traveling through the vacuum, but we predict theoretically that tachyon-like objects exist as faster-than-light ‘quasiparticles’ moving through laser-like media.
(That is, they exist as particle-like excitations, similar to other quasiparticles called phonons and polaritons that are found in solids. ‘Laser-like media’ is a technical term referring to those media that have inverted atomic populations, the conditions prevailing inside a laser.
) «We are beginning an experiment at Berkeley to detect tachyon-like quasiparticles. There are strong scientific reasons to believe that such quasiparticles really exist, because Maxwell’s equations, when coupled to inverted atomic media, lead inexorably to tachyon-like solutions.
«Quantum optical effects can produce a different kind of ‘faster than light’ effect (see «Faster than light?» by R. Chiao, P. Kwiat, and A. Steinberg in Scientific American, August 1993). There are actually two different kinds of ‘faster-than-light’ effects that we have found in quantum optics experiments.
- (The tachyon-like quasiparticle in inverted media described above is yet a third kind of faster-than-light effect
- ) «First, we have discovered that photons which tunnel through a quantum barrier can apparently travel faster than light (see «Measurement of the Single-Photon Tunneling Time» by A
Steinberg, P. Kwiat, and R. Chiao, Physical Review Letters, Vol. 71, page 708; 1993). Because of the uncertainty principle, the photon has a small but very real chance of appearing suddenly on the far side of the barrier, through a quantum effect (the ‘tunnel effect’) which would seem impossible according to classical physics.
The tunnel effect is so fast that it seems to occur faster than light. «Second, we have found an effect related to the famous Einstein-Podolsky-Rosen phenomenon, in which two distantly separated photons can apparently influence one anothers’ behaviors at two distantly separated detectors (see «High-Visibility Interference in a Bell-Inequality Experiment for Energy and Time,» by P.
Kwiat, A. Steinberg, and R. Chiao, Physical Review A, Vol. 47, page R2472; 1993). This effect was first predicted theoretically by Prof. Franson of Johns Hopkins University. We have found experimentally that twin photons emitted from a common source (a down-conversion crystal) behave in a correlated fashion when they arrive at two distant interferometers.
- This phenomenon can be described as a ‘faster-than-light influence’ of one photon upon its twin
- Because of the intrinsic randomness of quantum phenomena, however, one cannot control whether a given photon tunnels or not, nor can one control whether a given photon is transmitted or not at the final beam splitter
Hence it is impossible to send true signals in faster-than-light communications. «I refer interested readers to our paper ‘Tachyonlike Excitations in Inverted Two-Level Media’ by R. Chiao, A. Kozhekin, and G. Kurizki, Physical Review Letters, Vol. 77, page 1254; 1996, and references therein..
Can a wire run out of electrons?
Circuits don’t create, destroy, use up, or lose electrons. They just carry the electrons around in circles. For this reason, circuit electrical systems can’t really run out of electrons. The energy delivered through a circuit is not the result of electrons existing in the circuit.
What is electricity made up of?
What Is Electricity? — Electricity is a form of energy. Electricity is the flow of electrons. All matter is made up of atoms, and an atom has a center, called a nucleus. The nucleus contains positively charged particles called protons and uncharged particles called neutrons.
The nucleus of an atom is surrounded by negatively charged particles called electrons. The negative charge of an electron is equal to the positive charge of a proton, and the number of electrons in an atom is usually equal to the number of protons.
When the balancing force between protons and electrons is upset by an outside force, an atom may gain or lose an electron. When electrons are «lost» from an atom, the free movement of these electrons constitutes an electric current. Electricity is a basic part of nature and it is one of our most widely used forms of energy.
We get electricity, which is a secondary energy source, from the conversion of other sources of energy, like coal, natural gas, oil, nuclear power and other natural sources, which are called primary sources.
Many cities and towns were built alongside waterfalls (a primary source of mechanical energy) that turned water wheels to perform work. Before electricity generation began slightly over 100 years ago, houses were lit with kerosene lamps, food was cooled in iceboxes, and rooms were warmed by wood-burning or coal-burning stoves.
Beginning with Benjamin Franklin’s experiment with a kite one stormy night in Philadelphia, the principles of electricity gradually became understood. In the mid-1800s, everyone’s life changed with the invention of the electric light bulb.
Prior to 1879, electricity had been used in arc lights for outdoor lighting. The lightbulb’s invention used electricity to bring indoor lighting to our homes.
Are electrons moving?
With all of this in mind, an electron in a stable atomic state does not move in the sense of a solid little ball zipping around in circles like how the planets orbit the sun, since the electron is spread out in a wave. Furthermore, an electron in a stable atomic state does not move in the sense of waving through space.