When we convert a galvanometer into an ammeter we connect the resistance in parallel, the only reason we connect a resistance in parallel with galvanometer is so less current passes and the flow of current through galvanometer is slower but the same could be achieved with resistance in series.
$\begingroup$
$\endgroup$
Add a comment
|
1 Answer
$\begingroup$
$\endgroup$
A galvanometer is actually already an current measurement device (ampere meter). Often with resistance in the 10 to 100 Ohm range.
You would want a resistor in parallel if you want to measure higher currents. Say your galvanometer has an inner resistance of 100 Ohm and you put a 1 Ohm resistor in parallel. Then the current through the parallel resistor is a 100 times more then what flows through your galvanometer so for each 0.01 Ampere you see on the display you have an actual current of 1.01 Ampere.
If you put your resistor in series you make your galvanometer behave more like a voltmeter. It becomes less sensitive because the majority of the voltage is on the resistance in series (lets say 1000 Ohm) but on the other hand it draws less current from the circuit where you are measuring.
A typical modern multimeter has a resistance of 10M Ohms (10^7 Ohms) for voltage measurement while it has typical in the order of 0.1 Ohms for current (depending on the range)
