How many electrons are in 1mA ?

Thread Starter

RRITESH KAKKAR

Joined Jun 29, 2010
2,829
Hello,
How to find electrons flowing in few mA current?
example: 1mA how much electron are there?

charge on electron is = 1.6 x 10^-19C
Q=N*e
N=q/e
N=1/1.6x10^-19
n=0.625x10^19
 

DickCappels

Joined Aug 21, 2008
6,462
Can you take a try at this first? I think your question is best worded as "How many electrons per second does 1 milliamp represent."
 

Roderick Young

Joined Feb 22, 2015
408
One Ampere means that on average, one Coulomb of electrons are passing a given point per second, going in the same direction. If the same electron loops around and passes that point again, it counts as another one.

One milliamp is 10^-3 amp, which means that 10^-3 Coulombs are passing that point.

A Coulomb is a large number, about 6.24 x 10^18.

So one milli-Amp means 6.24 x 10^15 electrons per second passing through a given point.
 

Roderick Young

Joined Feb 22, 2015
408
Then what is Voltage ?
10V 20V are they presure or moving speed of electrons?
Voltage can be thought of as pressure. Current can be thought of as volume of flow. The actual speed of individual electrons is not something that usually matters in electronics, although it might in physics. Although an electric field propagates at basically light speed, electrons have a surprisingly low average velocity in the wires in our electronics, I've heard.

LED take ~20mA that mean 1.25x10^17 electrons.
If this is homework or for a test, be very careful about units. Current has the units of charge / time, in the above case, electrons per second. In a casual conversation, an engineer might know what you mean, but it is technically incorrect, and would likely be marked wrong on a test.
 

crutschow

Joined Mar 14, 2008
25,131
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Although an electric field propagates at basically light speed, electrons have a surprisingly low average velocity in the wires in our electronics, I've heard.
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Yes, the slow movement of electrons in a wire at typical current levels is because there are many more free electrons in a volume of the wire conductor (assuming 1 per atom) than there are in a coulomb of charge moving through that conductor.
 
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