JEE Main 2025 — 28 January, Morning Shift — Question 70

Given $\mathrm{R}_{2}=2 \mathrm{R}_{1}$

$M_{1}=\sigma \times \pi R_{1}^{2}=M_{o}$

$\mathrm{M}_{2}=\sigma \times \pi \mathrm{R}_{2}^{2}=\mathrm{M}_{\mathrm{o}}$

$\mathrm{M}_{2}=\sigma \times \pi \mathrm{R}_{2}^{2}=\sigma \times \pi\left[2 \mathrm{R}_{1}\right]^{2}=\sigma \times 4 \pi \mathrm{R}_{1}^{2}=4 \mathrm{M}_{\mathrm{o}}$

$\frac{I_{1}}{I_{2}}=\frac{\frac{\mathrm{M}_{1} \mathrm{R}_{1}^{2}}{2}}{\frac{\mathrm{M}_{2} \mathrm{R}_{2}^{2}}{2}}=\frac{\mathrm{M}_{1} \mathrm{R}_{1}^{2}}{\mathrm{M}_{2} \mathrm{R}_{2}^{2}}=\frac{1}{4} \times \frac{1}{4}=\frac{1}{16}$

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