question_answer

Two rings of radius R and n R made up of same material have the ratio of moment of inertia about an axis passing through centre is \[4\]. The value of n is

A)  \[\frac{1}{2}\]                                  

B)  \[60m\]

C)  \[50m\]                              

D)  \[30m\]

Correct Answer: A

Solution :

                Ratio of moment of inertia of the rings \[2.80\times {{10}^{5}}\] \[{{10}^{4}}\Omega \] (\[10\Omega \] = linear density of wire = constant) \[4.62\times {{10}^{-2}}\]             \[2.03\times {{10}^{-2}}\] (given) \[3.16\times {{10}^{-2}}\]             \[5.62\text{ }\times {{10}^{-2}}\]     \[\lambda \]     \[\lambda \,\,\,\,\pi {{r}^{3}}\frac{dB}{dt}\]