In a uniform magnetic field of $0.049 \mathrm{~T}$, a magnetic needle performs $20$ complete oscillations in $5$ seconds as shown. The moment of inertia of the needle is $9.8 \times 10^{-5} \mathrm{~kg} \mathrm{~m}^2$. If the magnitude of magnetic moment of the needle is $x \times 10^{-5} \mathrm{Am}^2$, then the value of ' $x$ ' is :
  • A$128 \pi^2$
  • B$50 \pi^2$
  • C$1280 \pi^2$
  • D$5 \pi^2$
NEET 2024, Medium
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