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A spherical source of power $4 W$ and frequency $800 Hz $ is emitting sound waves. The intensity of waves at a distance $200 m$ is
  • A$8 \times {10^{ - 6}}\,W/{m^2}$
  • B$2 \times {10^{ - 4}}\,W/{m^2}$
  • C$1 \times {10^{ - 4}}\,W/{m^2}$
  • D$4\,W/{m^2}$
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