An ammeter of resistance 13Ω is graduated up to 100A. After an additional shunt is connected, it can read up to 750A. Find the shunt resistance:
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An ammeter of resistance 13Ω is graduated up to 100A. After an additional shunt is connected, it can read up to 750A. Find the shunt resistance:

G1 Physics · Accepted Answer

Step 1: Ammeter's original full-scale current is I(g)=100A through meter resistance 13Ω. Step 2: For new total range I=750A, parallel shunt must carry I(shunt)=750−100=650A at same voltage. Step 3: I(g)G=I(shunt)S ⇒ S=(100×13)/650=2Ω. Correct A. Final answer: (A) 2Ω.