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MHT CET Medical202625 April 2026Morning ShiftPhysicsCurrent ElectricityActual

When a galvanometer is shunted with a 2 resistance, the deflection is reduced to one-fourth. If the galvanometer is further shunted with a 1 resistance, the further reduction in deflection is a fraction x of the deflection observed when shunted with 2 . Find x , assuming the main current I remains the same.

Options

  1. A3 5
  2. B5 3
  3. C2 3
  4. D1 3

Correct answer

A. 3 5

Step-by-step solution

Let the resistance of the galvanometer be G and the main current be I . When the galvanometer is shunted with S₁ = 2 , the deflection is reduced to one-fourth. This means the current through the galvanometer is I_ g1 = I 4 . Using the formula for current division, I_ g1 = S₁ G + S₁ I I 4 = 2 G + 2 I G + 2 = 8 G = 6 When the galvanometer is further shunted with a 1 resistance, this new resistor is connected in parallel with the existing 2 shunt. The new equivalent shunt resistance S₂ is: S₂ = 2 1 2 + 1 = 2 3 The new

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