# a mili ammeter whose resistance is 120 ohm has full scale deflection in the current of 5 mili A. how will you use it to measure Maximum current find the resistance of the mili ammeter ?value of Maximum current is 50 mili A

Given,

Resistance of the ammeter, G = 120 ohm

Maximum current for full scale deflection, I = 5 mA

In order to show full deflection for 50 mA current, A shunt resistance must be connected in parallel so that 50 - 5 = 45 mA current passes through the shunt S.

Now since the ammeter and the shunt are connected in parallel, so the voltage developed across the ammeter and the shunt S will be same.

Thus,

$5mA\times 120\Omega =45mA\times S\phantom{\rule{0ex}{0ex}}S=\frac{5mA\times 120\Omega}{45mA}=\frac{120}{9}=\frac{40}{3}=13.33\Omega $

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