A cell having a steady emf of 2 volt is connected across the potentiometer wire of length 10m. The potentiometer wire is of manganine and having of $11.5\Omega /m$. A new resistance of $5\Omega$ with negligible length is put in series with the potentiometer wire.
What is total resistance of wire?
Answer & explanation
Correct answer: option 4
$\text{Resistance per unit length of wire }= 11.5\Omega /m$
Length of wire = 10 m
$\text{ Resistance of wire }= 11.5 \times 10 = 115\Omega$
$\text{ Total resistance }= 115 + 5 = 120 \Omega$