Physics - Current Electricity Question with Solution | TestHub

In the first case: $R=12\Omega$ and $S=36\Omega$ In balanced condition, $\frac{R}{S}=\frac{1}{100-l}$ or $\frac{12}{36}=\frac{l}{100-l}$ or $3l=100-l$ or $4l=100\Rightarrow l=25\mathrm{cm}$ Therefore, first balance point is $l_1=25\mathrm{cm}$ In the second case: $R=36\Omega$ and $S=12\Omega$ In balanced condition, $\frac{R}{S}=\frac{l}{100-l}$ or $\frac{36}{12}=\frac{1}{100-1}$ or $l=300-3l$ or $4l=300\Rightarrow l=l_2=75\mathrm{cm}$ Therefore, second balance point is $l_2=75\mathrm{cm}$ The shift $=l_2-l_1=(75-25)\mathrm{cm}=50\mathrm{cm}$