# Thought of the day_16_Speed of light

Which is faster?
1) Light
2) Current
3) Both move with equal speed

Note by Rohit Gupta
5 years, 8 months ago

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Current means movement of charged particle; charged particle means mass ;and mass means that the particle can never reach the speed of light.....the max. speed it can reach is 99.9999% the speed of light. So I think the correct answer would be light.

- 5 years, 8 months ago

Ordinary electric current in a wire is quite slow. Way way slower than light in vacuum, for example. Like the difference between a horse drawn wagon and the ISS in orbit. No, make that a snail and the ISS.

Edit: Even though electron drift velocity in a typical wire is very slow (in the order of fractions of a millimeter per second), the speed of the change in the electric field in a wire can approach light-like speeds. If this weren't true, electronic computers wouldn't be so fast. As an analogy, air molecules in the atmosphere takes a while to go from place to place, we call it "wind". But sound waves travel far faster than wind.

- 5 years, 8 months ago

The beauty of this question hidden behind the actual definition of current. Flow of electric current is fastest among other currents. In our books we often study the electric current means the flow of electric charge. It meant that its the flow of electric charge and not electric charge carriers which is very slow, we cant even compare its speed to that of flow of charges in a current.

So In my opinion their speeds are equal.

- 5 years, 8 months ago

Charge usually travels quite slowly in a wire due to the fact that $\ V = \frac{I}{nAq}$ (V = drift velocity, n = number of charge carriers, A = area of wire and q = electron charge = 1.6 $\times$ $\ 10^{-19}$ C ) and $\ R = \rho \frac{L}{A}$ ( R = resistance in wire, $\rho$ = resistivity and L = length of wire) because in the 1st equation we need a small area to produce a fast current but this causes more resistance. All other factors all limited by electrical capacity, resistivity of materials etc... Even if we propelled the charged particles they still have mass and hence will never reach the speed of light (they can get very close though).

- 5 years, 8 months ago

speed of charge particle is different from speed of current..

- 5 years, 8 months ago

I think that in an ideal case they will have the same speed of light

- 5 years, 8 months ago

well....can you explain..how??

- 5 years, 8 months ago

Lmao are you people serious

- 5 years, 8 months ago

Think so light

- 5 years, 8 months ago

The speed of current has multiple meanings. In everyday electrical and electronic devices, the signals or energy travel as electromagnetic waves typically on the order of 50% to 99% of the speed of light, while the electrons themselves move (drift) much more slowly.So ,the answer in an ideal case (i.e when resistance of conductor is 0),electron i.e current move with speed of light.

- 5 years, 8 months ago

I didn't like the thought(aka thought) as it is not clear. "Which is faster" is a really bad question to ask. In what medium? It must be specified otherwise it will lead to misconception now that the theory of relativity has become much more common.

- 5 years, 8 months ago

This question really doesn't want to test about the medium..as speed of current is not the speed of electrons..its the speed of electrons which will be affected.. current will spread with the speed with which electric field is setup in the conductor...In conductors field is said to be spreading with speed of light..thus both of them should be equal..

- 5 years, 8 months ago

It's cannot be the same speed since the speed of spreading field is "about" the speed of light, so, it's not exactly the same. Also what do you define to be the "speed" of current? You have to state your question more clearly and according to Relativity, you can't have any types of information propagating at fatser speed than light.

- 5 years, 8 months ago

Exactly. That's what I was saying.

- 5 years, 8 months ago

In a same media

- 5 years, 8 months ago

For my words it's the speed of light which is faster

- 5 years, 8 months ago

1

- 5 years, 8 months ago

Light

- 5 years, 8 months ago

I think it Both Light and Current:

It could be Current given a ideal medium or conducter . Because in an ideal cylindrical conducter (it could be of any shape , I took cylindrer to make my point clear ) which is filled with electrons and without any resistance or bond , the moment a electron enter , another electron would be pushed out from other side , that too in the time it would require oight to get from the point to ther point because electromagnetic and electrostatic effects travel at speed of light .

On the other hand light has same speed .

So both have equal speed.

- 5 years, 8 months ago

Light

- 5 years, 8 months ago

Light is faster

- 5 years, 8 months ago

I think it is light..as no material can exceed the speed of light

- 5 years, 8 months ago

Guys don't get confused with the speed of current with speed of charges..

- 5 years, 8 months ago

.
1) An electric field doesn't necessarily mean that "charges" are "flowing out somewhere". Think radio towers
2) Current is about moving charges
3) Changes in an electric field can move at light speeds, but that does not mean electrons move at light speeds too. Relativity makes it impossible for electrons to move at light speed
4) "Flow of electrons" has many different meanings. Do we mean the speed of individual electrons, or the group, or drift, speed of electrons? In any case, it's USUALLY far slower than speed of changes in EM field, i.e. e.g. light, or changes in EM in a conducting wire. Just because the drift speed of electrons in a wire is sub-millimeters per second, that does not mean it takes an hour to turn off a ceiling light.

- 5 years, 8 months ago

no matter how fast it spreads into a medium....it can never exceed the speed of light...

- 5 years, 8 months ago

Can that be equal to the speed of light??

- 5 years, 8 months ago

SPEED OF LIGHT

- 5 years, 8 months ago

Current! Because it the source of Light!!

- 5 years, 8 months ago

Current is not the source of light always.Think of the sunlight.Is that because of current?

- 5 years, 8 months ago

Light

- 5 years, 8 months ago

Current

- 5 years, 8 months ago

Light

- 5 years, 8 months ago

Light

- 5 years, 8 months ago

Light

- 5 years, 8 months ago

Light

- 5 years, 8 months ago

Light

- 5 years, 8 months ago

Light

- 5 years, 8 months ago

Light

- 5 years, 8 months ago

Light of course.

- 5 years, 8 months ago

Light is faster. Electrical current means moviment of electrons or ions which have mass and particles with mass can't reach the speed of light.

- 5 years, 8 months ago

Light is an electromagnetic wave, hence no matter only energy, whereas current is movement of electrons and ions in the conductor which behave as matter in this case hence is SLOWER than the em wave.

- 5 years, 8 months ago

1

- 5 years, 8 months ago

All right, all right, once again, an "electric current" involves moving charged particles, which are fermions, not bosons, and thus are difficult to accelerate to anything like the speed of light. Nevertheless, at the LHC facility at CERN, protons are accelerated to about 0.99999999 the speed of light. Still, in vacuum, light moves faster.

- 5 years, 8 months ago

1

- 5 years, 8 months ago

Light

- 5 years, 8 months ago

Both move approx equal speed but light is slightly faster

- 5 years, 8 months ago

That is light

- 5 years, 8 months ago

Under certain circumstances you could increase the speed of current by decrease the temperature and decrease the speed of light by passing it through a dense Medium . the speed of current is increased by using helium to cool it down to make it a super electro magnet

- 5 years, 8 months ago

Light

- 5 years, 8 months ago

1 - light

- 5 years, 8 months ago

Light

- 5 years, 8 months ago

1

- 5 years, 8 months ago

Light

- 5 years, 8 months ago

I think light ,is it right?

- 5 years, 8 months ago

Light travels at 299792458 m/s 1.0A in a Copper wire would travel at approximately 0.0023 cm/s

- 5 years, 8 months ago

Light is faster then current

- 5 years, 8 months ago

Lighg

- 5 years, 8 months ago

Both... considering superconductor

- 5 years, 7 months ago

Light

- 5 years, 7 months ago

Abviously light

- 5 years, 7 months ago

Light

- 5 years, 6 months ago

Example:In high-vacuum(-0.00007651 m(e.gr)/f.gr•2) if the strenght of foton/electron emission is equal for example 220v=6000lum then Light and Electricity would have the same speed as their particle energy level.Light 300,000,000 m/s - Electricity 750,000 m/s•2.

- 5 years, 4 months ago

1

- 5 years, 3 months ago

Light

- 5 years ago

3) Both move with equal speed

- 4 years, 9 months ago

Light

- 5 years, 8 months ago

Light

- 5 years, 8 months ago

Current

- 5 years, 8 months ago

Light

but I think current flows through a medium. Without medium current never exists. So its speed depends upon medium which justifies that current flow will vary in different mediums.

While light on the other hand needs no medium to travel so its speeds vary's minutly with medium change.

So according to my understanding they are completely different entitied and can not be compared for any of thier properties

- 5 years, 8 months ago

Light is faster. Speed of light is around 3 × 10^8 m/s. But current has a speed of only some millimeters per second..

- 5 years, 8 months ago

3) in ideal cases

- 5 years, 5 months ago

1.light

- 5 years, 3 months ago