A potentiometer wire of length $1\,\,m$ and resistance $10\,\,{\rm{\Omega }}$ is connected in series with a cell of $emf\,\,2\,\,V$ with internal resistance $1\,\,{\rm{\Omega }}$ and a resistance box including a resistance $R.$. If potential difference between the ends of the wire is $1\,\,mV$, the value of $R.$ is

NEET UG PHYSICS MCQ: CURRENT ELECTRICITY

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Application +4 | -1

A potentiometer wire of length

1\,\,m

and resistance

10\,\,\mathrm{\Omega }

is connected in series with a cell of

emf\,\,2\,\,V

with internal resistance

1\,\,\mathrm{\Omega }

and a resistance box including a resistance

R.

. If potential difference between the ends of the wire is

1\,\,mV

, the value of

R.

View answer and explanation

Correct option: B

19989\,\,\mathrm{\Omega }

Option B (both bulbs will fuse) is correct because when connected in parallel to 240V, each bulb experiences twice its rated voltage, leading to excessive power and fusing.

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