Q. A galvanometer of resistance G is shunted by a resistance S ohm. To keep the main current in the circuit unchanged, the resistance to be put in series with the galvanometer is
A) G²/(S + G)
B) G/(S + G)
C) S²/(S + G)
D) SG/(S + G)
Explanation
[Solution from source] For the main current to stay unchanged, the shunted galvanometer plus the series resistance must still equal G. The shunted combination is GS/(G + S), so R = G − GS/(G + S) = G²/(G + S). The answer GS/(G + S) is only the shunted combination itself, not the extra resistance needed. Answer (1).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.