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COMEDK · Physics · 19. Current Electricity

Two identical moving coil galvanometers have \(10 \Omega\) resistance and full-scale deflection at \(2 \mu \mathrm{A}\) current. One of them is converted into a voltmeter of range \(10 \mathrm{~mV}\) and the other into an ammeter of range \(1 \mathrm{~mA}\) using appropriate resistors. The ratio of resistance of the converted voltmeter to that of the ammeter is

  1. A 25000 : 1
  2. B 250000 : 1
  3. C 2500 : 1
  4. D 5000 : 1
Verified Solution

Answer & Solution

Correct Answer

(B) 250000 : 1

Step-by-step Solution

Detailed explanation

The resistance of the galvanometer is \(G = 10 \Omega\) and the full-scale deflection current is \(I_g = 2 \times 10^{-6} \text{ A}\). For the voltmeter, the range is \(V = 10 \text{ mV} = 10^{-2} \text{ V}\). The total resistance of the voltmeter is…