Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE MainPhysicsCurrent Electricity

A galvanometer of resistance G is converted into an ammeter of range I by connecting a shunt of resistance S . To double the range of this ammeter to 2I , an additional resistor R is connected in parallel with the existing shunt. The value of R is:

Options

  1. AS
  2. BS 2
  3. CGS G+S
  4. DGS 2(G+S)

Correct answer

C. GS G+S

Step-by-step solution

For the initial ammeter of range I , the maximum current I_g through the galvanometer satisfies: I = I_g + I_s = I_g + I_g G S = I_g (1 + G S ) Let S_ eq be the new equivalent shunt resistance when R is connected in parallel with S . For the new range 2I , we have: 2I = I_g (1 + G S_ eq ) Substituting the expression for I into the second equation: 2 (1 + G S ) = 1 + G S_ eq 2 + 2G S = 1 + G S_ eq G S_ eq = 1 + 2G S 1 S_ eq = 1 G + 2 S Since S_ eq is the parallel combination of S and R , we know 1 S_ eq = 1 S + 1 R

Practice Current Electricity on Quantrex Academy →

More from Current Electricity

A metal wire of cross-sectional area 0.5 mm ^2 and length 100 m is connected across a battery of e.m.f. 2 V and internal resistance 1 . The density, atomic mass and electrical cond 2026As shown in the figure, the resistance of a galvanometer G can be found by the half-deflection method. Here the resistance R₂ is adjusted such that when the key K is closed the def 2026The stored charge in the capacitor in steady state of the following circuit is ________ C. 2026A moving coil of galvanometer when shunted with 2 , resistance gives a full scale deflection for a current of 500 mA. When a resistance of 470 , is connected in series it gives a f 2026Two cells of emfs 1 V and 2 V and internal resistance 2 , and 1 , , respectively connected in parallel, gave a current of 1 A through an external resistance. If the polarity of one 2026Refer to the circuit diagram given below. The heat generated across the 6 , resistance in 100 second is 100 J. The value of is _______. (Nearest integer) 2026In an experiment to determine the resistance of a given wire using Ohm's law, the voltmeter and ammeter readings are noted as 10 V and 5 A , respectively. The least counts of voltm 2026Under steady state condition the potential difference across the capacitor in the circuit is _______ V. 2026 Full Current Electricity list All JEE Main PYQs