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Saturday, 31 October

JEE Main 2022 · PhysicsNumerical answerNumerical valueMediumData or graph

JEE Main 30 June 2022, Shift 1, Physics Q56

Question 56 of 90 in this shift, Physics question 26 of 30, Section B.

The circuit diagram of potentiometer used to measure the internal resistance of a cell (E) is shown in figure. The key ‘K’ is kept closed so as to send constant current through potentiometer wire. When key ‘K1\mathrm{K_1}’ is kept open the null point is found to be at 120 cm on the potentiometer wire. When the key ‘K1\mathrm{K_1}’ is closed the null point is shifted at 80 cm at the potentiometre wire. The internal resistance of the given cell is __________ Ω\Omega.

The figure, in words

Potentiometer circuit: upper loop with a 4 V cell, a key K and a rheostat Rh connected across the wire AB; below it the cell E=1.5 V connected to the wire through a galvanometer G and a jockey (arrow touching the wire), with a 4 ohm resistor and key K1 in the lower branch across the cell.

Official answer

2

NTA final key.

Chapter
Current Electricity
Topic
Potentiometer
Idea tested
Internal Resistance Measurement

Same idea in other shifts

Asked 3× in all
  1. 4 Apr 2024, Shift 1 · Q50To measure the internal resistance of a battery, potentiometer is used. For R=10 ΩR = 10\ \Omega, the balance point is observed at l=500l = 500…MediumSingle correct
  2. 27 Jun 2022, Shift 1 · Q55A cell, shunted by a 8 Ω8\ \Omega resistance, is balanced across a potentiometer wire of length 3 m. The balancing length is 2 m when the…MediumNumerical value

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.