In an experiment to determine the period of a simple pendulum of length 1 m, it is attached to different spherical bobs of radii r_1 and r_2. The two…

In an experiment to determine the period of a simple pendulum of length $\displaystyle 1$ m , it is attached to different spherical bobs of radii $\displaystyle \mathrm{r}_1$ and $\displaystyle \mathrm{r}_2$. The two spherical bobs have uniform mass distribution. If the relative difference in the periods, is found to be $\displaystyle 5 \times 10^{-4} \mathrm{~s}$, the difference in radii, $\displaystyle \left|\mathrm{r}_1-\mathrm{r}_2\right|$ is best given by :