Question

is electricity's speed instantaneous?

Answer 1

nope.

Answer 2

even light is not instantaneious

Answer 3

lol physics.

Answer 4

if i have a switch in canada that connects to a lamp in china, as soon as i turn on the switch, at the same time, the lamp will light on, right?

Answer 5

you will have some delay,

Answer 6

it'll take a really short time, but not instantaneous.

Answer 7

Think about it this way, have you ever seen when you plug in something into an outlet and there's a spark. that's the electricity traveling...or better yet, think about lightning.

Answer 8

why delay? I mean, looking at the atomic structure of a electricity line. When i turn on the switch, the first electron will push the second one, and the second one will push the third one, the third one push the fourth one, ALL AT THE SAME TIME. So when the 1st one (at canada) moves, the last one (at china) will also move. Thus, the lamp will light on at soon at the switch turns on...

Answer 9

That is true. but wouldnt you agree that it takes time for that first electron to push?

Answer 10

Now that's going into quantum stuff. It get's really weird there, but there is a delay.

Answer 11

yea but as soon as u turn on the switch, the first electron will push lol

Answer 12

yeah and that takes time....there isn't really an argument in this. speed of signal propagation is close to that of light, or about a foot per nanosecond.

Answer 13

imagine the electricity line like a train, the first wagon is in Canada, the last wagon in China. Thus, the entire train is always moving at the same time..

Answer 14

Why not ask "If I have a giant metal pole that's 2 light years long, and I push this end of it, wouldn't the other end move at the same time?"

The answer is no. Because of weird things that happen with atoms of the metal interacting at a speed less than the speed of light.

Answer 15

its weird

Answer 16

okay if you are using that chain argument, it isn't the electron where you that is moving all the way to china. It is ALL THE ELECTRONS in that chain moving that small distance. The elctron where you are never traveled all the way to china

Answer 17

It is a flow.

Answer 18

We actually don't use a direct current we use alternating current. So if goes back and forth.

Answer 19

@Puzzhang it's totally true, however, as soon as the first one moves, the last one responds, and lights up the light. The first one doesn't need to travel all the way to China.

Answer 20

well, electric field travels at the speed of light. when you have switched a circuit on, it means that you have switched the electric field on , which in turn creates motion in the locally free charged particles

Answer 21

And you can slow that flow with resistors.

Answer 22

It takes time for the signal to propagate from the first electron to the last electron. It's quick, but not instantaneous. Like I said before, this is basically the same thing as the question

"If I have a giant metal pole that's 2 light years long, and I push this end of it, wouldn't the other end move at the same time and thus propagate the signal instantaneously?"

The answer is no. It doesn't propagate instantly.

Answer 23

Special relativity.

Answer 24

no, you cannot slow the propagating field. resistors only dissipate the energy of the charged particles. they don't slow the field down. special relativity is not what we are speaking about.@Romero

Answer 25

so if i have a metal pole that's 100m long, I push one end, does the other end move at the same time?

Answer 26

no it doesn't. there always is a lag

Answer 27

so if i have a single atom in my hand, I push one end, does the other end move at the same time?

Answer 28

even then it will only move at the speed it is moving at on your end as you push it which will never be an instantaneous blink from one position in space to another.

Answer 29

@Puzzhang yes, but as one end moves, the other end moves at the same time, don't you agree?

Answer 30

of course it takes time from the first end to travel from one space to another, but the WHOLE THING, thus(one end of the atom, and the other end of the atom) will move at same time

Answer 31

Even then, it won't move at exactly the same time because there are other forces slowing it down.

Answer 32

what about this, think that metal pole is falling from the earth vertically, when one end moves, don't you agree that the other end moves at the same time. Or else the metal pole will stretch out

Answer 33

hey, don't go to atomic level, because nobody has seen how it looks like. all we have is some gentlemen predictions of its shape

Answer 34

if you are creating a gravity field in which the whole field will act on the atom, then everything moves at the same time.

however in your example of using a hand pushing an atom. you'd be using photons which would naturally push against the electromagnetic field or w/e which would then push the nucleus.

Answer 35

In gravity, the metal pole does stretch out actually.

Answer 36

a metal pole does stretch out while falling under gravity

Answer 37

@vamgadu No it doesn't

Answer 38

so the satellite that's continuously falling down to Earth due to gravity, is going longer and longer and longer. Same thing will the whole solar system, everything is stretching out constantly

Answer 39

@Romero can you prove that it doesn't?

Answer 40

What do you mean by this "is going longer and longer and longer"

Answer 41

It's not stretching out any more. While under increasing/decreasing gravity, it's length appears to change. If it's under a constant gravitational field, the length appears to stay the same.

Answer 42

streching out

Answer 43

Objects have their own gravity that keep them solid.

Answer 44

yes they do, so do you think the pen thats right now in my hand is together because of gravity?

Answer 45

then explain why doesn't car stretch out?

Answer 46

No it's because of normal forces

Answer 47

gravity is a week force when considering very small bodies of low density

Answer 48

Because our atomic structure is strong enough to prevent the force of gravity from stretching us out.

Answer 49

so if you are considering a metal rod, can we agree that its held together because of the bond forces (what ever) that are existing between neighbouring atoms?

Answer 50

ok let's be clear here:
1) A metal pole 1000 meters long, if I push one end of it, the other end will NOT move at the same time
2) A car, if I push one end, will the other end move at the same time?

Answer 51

no it takes time

Answer 52

for the force to travel unless you are applying an impulse

Answer 53

then how long exactly is the delay?

Answer 54

long enough for the electrons in the front to experience force enough to move

Answer 55

and that force's speed < speed of light, is that what you are saying?

Answer 56

Force doesn't have speed....

Answer 57

Is that right?

Answer 58

yes its right
but the effect of it has speed

Answer 59

so if i have an object that's 3x10^8m long, when one end moves, the other end will move in ONE second, assuming that the 'effect of it' travels at the speed of light

Answer 60

I think I have heard this question before but said differently. Like if you have a strong enough laser to see it when you point to the moon if you move the laser slightly then the laser on the moon moves really fast, faster than the speed of light.

Answer 61

speed here does not imply distance by time
you cannot really say how long the effect takes to reach the final point.if you take a quintal of mercury , because of viscousity it has, the effect may die down in between

Answer 62

how can the point move so fast?
if you have moved the laser, then that information is carried by light to the final point which itself travels at c. so are you telling me that before getting the information itself the light has moved to the final point and reaches its new position?

Answer 63

electron speed is actually preaty slow, what is fast is the transmition of magnetic field, which moves at speed of light

Answer 64

@myko but the question that's intriguing is, if i have metal pole that's 100m long, when i push one end, does the other end move at the same time?

Answer 65

hmm.... I guess not. Since any fisical body has some elasticity , that can be very small. That means it would take time to transmit the force from one end to the other