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

In an experiment to determine the value of an unknown resistance R , a student uses a voltmeter and an ammeter. The voltmeter is constructed by connecting a galvanometer of resistance G in series with a high resistance R₁ . The ammeter is constructed by connecting an identical galvanometer in parallel with a low resistance R₂ . The voltmeter is connected in parallel across R , and the ammeter is connected in series w

Options

  1. AV I
  2. BV I - V R₁
  3. CV I - V G + R₁
  4. DV I - G R₂ G + R₂

Correct answer

C. V I - V G + R₁

Step-by-step solution

The voltmeter is connected in parallel with the unknown resistance R . The total resistance of the voltmeter is R_V = G + R₁ . The current drawn by the voltmeter is I_V = V R_V = V G + R₁ . The ammeter measures the total current I entering the parallel combination of the resistor and the voltmeter. By Kirchhoff's current law, the current flowing through the resistor R is I_R = I - I_V = I - V G + R₁ . Therefore, the true value of the resistance is R = V I_R = V I - V G + R₁ . Answer: V I - V G + R₁

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