Question

The potentiometer wire AB is 100 cm long. The value of R for which the galvanometer shown no deflection, when AC = 40cm shown in figure is

• A. 13$\Omega$
• B. 17$\Omega$
• C. 15$\Omega$
• D. 21$\Omega$

Answer 1

The correct option is C 15$\Omega$

The condition of no deflection of galvanometer : $\frac{10}{R}=\frac{AC}{BC}=\frac{40}{100-40}=\frac{2}{3}\Rightarrow R=15\Omega$