Yes, by definition a sigma field is closed under countable unions. Since countable disjoint unions are countable unions this is true directly by the definition.
See http://en.wikipedia.org/wiki/Sigma-algebra.
No, physics is not countable. It is a broad and complex field of science that encompasses various subfields and topics, making it difficult to quantify or categorize in a simple, countable manner.
There is no plural: neurology is a field of medicine, not a countable noun.
Yes, the noun load is a countable noun. The plural form is loads. example: It took three loads of soil to level the field.
"Rock" can be both countable and uncountable. When used in the singular form to refer to a single piece of rock, it is countable (e.g., "I found a rock on the beach"). When used in the plural form to refer to multiple pieces of rock in a general sense, it is uncountable (e.g., "There are rocks scattered across the field").
Magnetic field lines are closed curves, meaning they form continuous loops that originate from the north pole and loop back to the south pole of a magnet. This represents the continuous flow of the magnetic field in a closed loop.
Use "SCND" for field names relating to number two in a countable series (or 2nd) Use "SS" for field names relating to a duration of time expressed in seconds
yes yes
Yes, the magnetic field is a non-conservative field. This means that the work done by a magnetic field on a charged particle moving in a closed path is generally not zero, unlike a conservative field where work done in a closed path is zero.
Forbes Field closed on June 28, 1970.
The set of integers is not closed under multiplication and so is not a field.
Yes, but visible alcohol closed or not will prompt a field sobriety test in most cases.
Unite the Union are the recognized trade union for the field engineering work force in the U.K