  A recent physics challenge shows a circuit, where a voltmeter is connected in
series. Indeed, real voltmeters have finite input resistance, therefore one may
think that they can be used as resistors. In addition, voltmeters measure the
voltage difference between their terminals, therefore it seems to be possible
to calculate the current flowing through them. Is it okay? Does it make the
voltmeter more universal? Are there any hidden secrets? How it is related to
high-quality physics and STEM education, which are increasingly important in
the modern world? Doesn't it approve an improper use that one can never see in
any textbook and application? Suggesting and teaching such uncommon solutions
doesn't generate undesired attitude? On the other hand, can it make the
development of creativity and understanding harder if the students are taught
to follow always the application rules? We do think it bears some discussion.
