Can we measure this electric current? 10 electrons per second

[alpha2cen]

Is it possible to measure very very little current, i.c., 10 electrons per second? We can use amperemeter to measure ampere .

But how can we measure very small ampere. I think this instrument might be very useful to measure bio-electrical signal and nano-pore DNA sequencing.

Edited January 16, 2011 by alpha2cen

[John Cuthber]

Hypothetically, in ideal conditions you can measure currents that small. But it's not easy.

http://www.tmworld.com/article/319701-Femtoamp_fA_measurements.php

It will only work if the currents carry on for a reasonable length of time.

[alpha2cen]

Thank you for good answering.

But it is useful for big currunt 1x10^-15A.

How about this method? Electric charge storage an emitting method.

In the middle of the circuit we make some device for storage electric charge.

First, few minute we save the electric charge, and emitt the saved charge.

At this time we measure the current, and devide the current by the saving time.

Any good opinion?

[lemur]

Why do you think current can be measured in electrons/second? Isn't electricity a wave that travels through electrons in a conductor as its medium? I think what you should be asking is what is the minimum amount of energy that would need to be added to a conductor to create such a wave. Is it a plank-constant that can cause a ripple through a gold wire or is more energy needed (I assume more is needed but I don't know how much or why). I think each material should have a minimum energy-wave that is related to its atomic structure, but that is just a guess.

[Xittenn]

Most bio-electric signals are in the form of ions not electrons as I recall :/

[lemur]

Most bio-electric signals are in the form of ions not electrons as I recall :/

Meaning the ionization of a particle is transmitted as a wave through subsequent particles? Did someone else mention nerves or did you just decide to frame the issue in terms of them?

[alpha2cen]

Why do you think current can be measured in electrons/second? Isn't electricity a wave that travels through electrons in a conductor as its medium? I think what you should be asking is what is the minimum amount of energy that would need to be added to a conductor to create such a wave. Is it a plank-constant that can cause a ripple through a gold wire or is more energy needed (I assume more is needed but I don't know how much or why). I think each material should have a minimum energy-wave that is related to its atomic structure, but that is just a guess.

 

1A=coulomb/second, coulomb= electron number.

Electron current is not different electromagnetic wave flow.

Electron current is very slow in a conductor, but electromagnetic flow is very fast , it's speed is the same as light speed.

[lemur]

1A=coulomb/second, coulomb= electron number.

Electron current is not different electromagnetic wave flow.

Electron current is very slow in a conductor, but electromagnetic flow is very fast , it's speed is the same as light speed.

Please explain coulomb/second. You are not differentiating between atomic electrons and waves that travel as current through the conductor? Do you distinguish between water molecules and ocean waves? Between air molecules and sound waves? Are these flawed analogies? If so, why?

[alpha2cen]

Please explain coulomb/second. You are not differentiating between atomic electrons and waves that travel as current through the conductor? Do you distinguish between water molecules and ocean waves? Between air molecules and sound waves? Are these flawed analogies? If so, why?

 

Let us take a look this site.

http://www.slidefinder.net/e/electriccurrent/13274269

slide 6

It will be sufficient for your inquire.

[lemur]

Let us take a look this site.

http://www.slidefind...urrent/13274269

slide 6

It will be sufficient for your inquire.

Does "electron drift speed" refer to the speed of the current moving through the wire or something else?

[alpha2cen]

Real electron moving speed at the atom is not so slow, but it's movement through the conductor is very slow, i.e., conductor direction moving speed is slow. My question is "Can we storage very few electrons(60,000 ~ 100,000) accurately in the any device?"

[TonyMcC]

Nobody is mentioning thermal noise. I feel this will swamp any current that can be counted as a small number of electrons per second. It is cerainly a problem with very sensitive equipment such as radar receivers.

[ewmon]

Very little in life is actually measured directly, and I doubt that any method or device exists that can actually count the passage of ten electrons over the course of one second.

 

Instead, a device can accumulate/integrate the current over a period of time and then measure this captured charge. Or an amplifying device can amplify/cascade this current/electrons, and then, measure this magnified current/charge through more conventional means and scale it to the original current.

 

For example, this addresses some of the OP's criteria:

 

Recent improvements in CCD design have greatly diminished dark noise to negligible levels and reduced their contribution to total read-out noise to less than 10 electrons per pixel at room temperatures. ... Some room temperature cameras may have such a low dark signal that it can be ignored for integration periods of a second or less.

CCD Sensitivity and Noise

[TonyMcC]

In general amplifiers also amplify the input noise as well as the wanted input. Worse than that, they introduce extra noise from their own circuitry. This results in the signal/noise ratio at the output being worse than the input. Because of its random nature it is difficult to completely cancel noise effects. I'm not too sure whether today's technology can cope with this at such low levels of current.