The galvanometer deflection is θ₀ when key K₁ is closed and K₂ is open. When K₂ is also closed and R₂ is adjusted to 5 Ω, the deflection becomes θ₀/5. Neglect the internal resistance of the battery. Find the galvanometer resistance.

Question

G1 Physics · Accepted Answer

Deflection is proportional to galvanometer current. With K₂ open, galvanometer current = E/(220+G). With K₂ closed, the 5 Ω branch shunts the galvanometer. Current division with the new deflection equal to one-fifth of the original gives G = 22 Ω. Hence option D.