Is there a word for "becomes empty"?

After running a certain operation a value is taken from field A to field B. After the operation field A is empty. Is there a word or better phrase for this?

During the operation field A _________ [becomes empty].

Solution 1:

Andrew Leach is right in saying is emptied is better than empties here.

However, for your particular example, I’d suggest:

During the operation field a is cleared.

When relating to GUIs, it’s a much more common way of expressing that the content has been removed from an input field.

Solution 2:

The verb empty can be transitive or intransitive.

[with object] Remove all the contents of (a container)
[no object] (of a place) be vacated by people in it

[ODO]

Thus, the field empties.

Usually, though, where something happens as a result of something else (like a value being taken from a place), the action of an agent is implied by using the passive voice, is emptied.