Question

Why is it so that ammeter is always connected in a series connection and voltmeter is connected parallel to it ?

state and derive joule's law of heating effect

Answer 1

(i) The internal resistance of the ammeter is very low.If we connect it in series, then
the maximum current can flow through it. So the accurate current should be
measured. If we connect it in parallel then the accurate current can’t be
measured.

(ii) The internal resistance of the volt meter is very high and it is used to measure the
potential difference between the two points. If we connect it in series, then
there is no flow of current in the circuit because of high resistance. And no use
of connecting it in series because the potential difference between two points
on the same line is zero

https://www.google.co.in/amp/s/byjus.com/physics/joules-law/amp/