Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
NTA Abhyas JEE Main2020PhysicsCurrent ElectricityPractice

A potentiometer wire of length 10 cm and resistance 32 Ω is connected in series with a battery of EMF 2 . 5 V , internal resistance 3 Ω and external resistance R . If a secondary cell of 0 . 4 V is balanced at 8 cm length. Then value of R is

Options

  1. A100   Ω
  2. B110   Ω
  3. C105   Ω
  4. D115 Ω

Correct answer

D. 115 Ω

Step-by-step solution

Potential gradient of potentiometer = 2.5 ( 3 + R + 32 ) × 30 10 Balancing length for cell of emf e = 0.4 V is 8 cm . ∴ 2.5 ( 35 + R ) × 3 × 8 = 0.4 ⇒ 5 × 3 × 4 = 0.04 × ( 35 + R ) 10 ⇒ 15 × 10 = 35 + R ⇒ R = 115 Ω

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 NTA Abhyas JEE Main PYQs