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

A cell of emf 6 V and unknown internal resistance r is connected across a 4 resistor. A non-ideal voltmeter having a resistance of 12 is connected across the 4 resistor. If the voltmeter reads 3 V , the internal resistance r of the cell is _____ .

Correct answer

3

Step-by-step solution

The non-ideal voltmeter is connected in parallel with the 4 resistor. The equivalent resistance R_p of the voltmeter and the external resistor is: R_p = 4 12 4 + 12 = 48 16 = 3 The voltmeter reads the voltage across this parallel combination, which is V = 3 V . The total current I drawn from the cell is: I = V R_p = 3 3 = 1 A Using the equation for the complete circuit: E = I(R_p + r) 6 = 1 (3 + r) 3 + r = 6 r = 3 Answer: 3

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