The length of a potentiometer wire is $1200\; \mathrm{cm}$ and it carries a current of $60 \;\mathrm{mA}$. For a cell of $emf\;5\; \mathrm{V}$ and intemal resistance of $20\; \Omega,$ the null point on it is found to be a $1000\; \mathrm{cm} .$ The resistance of whole wire is .............. $\Omega$
  • A$120$
  • B$60$
  • C$80$
  • D$100$
JEE MAIN 2020, Medium
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