CBSE Class 10 Answered
An ammeter is used to measure the current in an electrical circuit. It is connected in series with the circuit and the resistance of an ammeter is to be made as low possible, as it is desired to measure currents in a electrical circuit without causing any appreciable potential drop. If it is connected in parallel with a circuit then it would cause a short circuit since the resistance of the ammeter is very low which will damage the ammeter or the circuit.
A voltmeter measures the potential difference across two points of an electrical circuit. It is connected in parallel to the branch across which the potential difference is to be measured. If it is connected in series, then the potential difference between the two points at the same line is zero and hence, the readings will always be zero.Also, the resistance of a voltmeter must be high so that a small magnitude of current that flows through the voltmeter does not alter the current conditions in the branch, across which it is to measure the potential difference.
So we always connect voltmeter in parallel and ammeter in series.