Current Electricity and Electrical InstrumentHard
Question
A micro ammeter has a resistance of 100 and a full scale range of 50 . It can used as a voltmeter or a higher range ammeter provided a resistance is added to it. Pick the correct range and resistance combination (s).
Options
A.50 V range with 10 kΩ resistance in series.
B.10 V range with 200 kΩ resistance in series.
C.5 mA range with 1Ω resistance in parallel.
D.10 mA range with 1Ω resistance in parallel.
Solution
For Ammeter IgG = (I - Ig)R
50 × 10-6 × 100 = 5 × 10-3 × (R) ⇒ R ≅ 1Ω
For voltmeter Ig (R + G) = V
⇒ 50μA (R + G) = 10V
⇒ R + G = 200 kΩ
⇒ R ≅ 200 kΩ
50 × 10-6 × 100 = 5 × 10-3 × (R) ⇒ R ≅ 1Ω
For voltmeter Ig (R + G) = V
⇒ 50μA (R + G) = 10V
⇒ R + G = 200 kΩ
⇒ R ≅ 200 kΩ
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