Search results
Results from the WOW.Com Content Network
Accuracy is also used as a statistical measure of how well a binary classification test correctly identifies or excludes a condition. That is, the accuracy is the proportion of correct predictions (both true positives and true negatives) among the total number of cases examined. [10]
The precision of the position is improved, i.e. reduced σ x, by using many plane waves, thereby weakening the precision of the momentum, i.e. increased σ p. Another way of stating this is that σ x and σ p have an inverse relationship or are at least bounded from below. This is the uncertainty principle, the exact limit of which is the ...
This glossary of physics is a list of definitions of terms and concepts relevant to physics, its sub-disciplines, and related fields, including mechanics, materials science, nuclear physics, particle physics, and thermodynamics.
In physics, there are equations in every field to relate physical quantities to each other and perform calculations. Entire handbooks of equations can only summarize most of the full subject, else are highly specialized within a certain field. Physics is derived of formulae only.
Derived quantities can be expressed in terms of the base quantities. Note that neither the names nor the symbols used for the physical quantities are international standards. Some quantities are known as several different names such as the magnetic B-field which is known as the magnetic flux density , the magnetic induction or simply as the ...
In experimental physics, there are always observational errors determining variables such as positions and velocities. So perfect prediction is practically impossible. Moreover, in modern quantum mechanics, Werner Heisenberg's indeterminacy principle puts limits on the accuracy with which such quantities can be known.
In a classification task, the precision for a class is the number of true positives (i.e. the number of items correctly labelled as belonging to the positive class) divided by the total number of elements labelled as belonging to the positive class (i.e. the sum of true positives and false positives, which are items incorrectly labelled as belonging to the class).
The atomic length scale is ℓ a ~ 10 −10 m and is given by the size of hydrogen atom (i.e., the Bohr radius, approximately 53 pm).; The length scale for the strong interactions (or the one derived from QCD through dimensional transmutation) is around ℓ s ~ 10 −15 m, and the "radii" of strongly interacting particles (such as the proton) are roughly comparable.