JEE Main 2019PhysicsCurrent ElectricityMediumMCQ

JEE Main 2019 — Current Electricity Question with Solution

JEE Main 2019 (12 Jan Shift 1)

Question

An ideal battery of emf 4V and resistance R are connected in series in the primary circuit of a potentiometer of length 1 m and resistance 5 Ω. The value of R, to give a potential difference of 5 mV across 10 cm of potentiometer wire, is:

Choose an option

Show full solutionCorrect option: C
Correct answer
C395 Ω

Step-by-step explanation

Potential gradient x=5×10-310×10-2=4R+5×51

⇒  120=20R+5

⇒  400=R+5

R=395 Ω

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About this question

This is a previous-year question from JEE Main 2019, covering the Current Electricity chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.