Ampere Could Be Redefined After Experiments Track Single Electrons Crossing Chip

ananyo writes "Physicists have tracked electrons crossing a semiconductor chip one at a time — an experiment that should at last enable a rational definition of the ampere, the unit of electrical current. At present, an ampere is defined as the amount of charge flowing per second through two infinitely long wires one meter apart, such that the wires attract each other with a force of 2×10^-7 newtons per meter of length. That definition, adopted in 1948 and based on a thought experiment that can at best be approximated in the laboratory, is clumsy — almost as much of an embarrassment as the definition of the kilogram, which relies on the fluctuating mass of a 125-year-old platinum-and-iridium cylinder stored at the International Bureau of Weights and Measures in Paris. The new approach, described in a paper posted onto the arXiv server on 19 December, would redefine the amp on the basis of e, a physical constant representing the charge of an electron."

Comments

Definition of a kilogram

[Infiniti2000]

A kilogram is straightforwardly defined as 2.20462 pounds. Simple enough.

Re:Definition of a kilogram

[trongey]

I guess I missed the humor tag in your original post.

That's OK. You were publicly correcting someone for the misuse of units of measure.
None of us expected you to have a functional sense of humor.

Re:yeah because imperial

[martinux]

Force was redefined in the prequels as midichlorians multiplied by anger. Conveniently it's kept the same equation:

f = ma

A modest editorial proposal

[TheloniousToady]

How about we change "At present, an ampere is defined as" to "Currently, an ampere is defined as"?

Re:Gravity is not constant...

[djdanlib]

A duck.