An ammeter movement reads 0 - 1mA FSD and has a coil resistance of 52.2 ohms. What would you be required to do to enable it to read 10mA FSD?
- Place a 5.8 ohm resistor as a shunt in parallel with the meter.
- Place a 52.2 ohm resistor as a shunt in parallel with the meter.
- Place a 9 ohm resistor as a multiplier in series with the meter.
Explanation from PART66Online
Extending a current range needs a shunt: a low-value resistor in parallel that carries the surplus current while the movement still takes only its own full-scale 1 mA. Rsh = Rm / (n - 1), where n is the multiplying factor 10 mA / 1 mA = 10, so Rsh = 52.2 / 9 = 5.8 ohms. A shunt equal to the coil resistance would only double the range, to 2 mA, and a multiplier in series is how a voltmeter range is extended, not an ammeter's.
V
vale asked · 6 Feb 2021
Can someone explain pls?
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