Sound intensity and the decibel scale

Answer Key - Grade 11 Science Worksheet - Challenge Me

Circle the best answer, or write your answer on the line.

1. 1.

   A sound reads 65 dB. What is its intensity, to 0.01 μW/m², Esme? Use I₀ = 10⁻¹² W/m².

   3.16 μW/m²
2. 2.

   A sound reads 52 dB. What is its intensity, to 0.01 μW/m², Jun? Use I₀ = 10⁻¹² W/m².

   0.16 μW/m²
3. 3.

   A sound reads 78 dB. What is its intensity, to 0.01 μW/m², Kira? Use I₀ = 10⁻¹² W/m².

   63.1 μW/m²
4. 4.

   A student says moving twice as far from a speaker halves the intensity. Which reply fits OpenStax, Milo?

   • Yes; intensity falls in step with distance
   • Yes; twice as far, half the sound energy per square meter
   • No; it falls to a quarter, as 1 ÷ r²
5. 5.

   A speaker gives 70 dB at 2 m. About what level is it at 4 m, Pia?

   • About 35 dB
   • About 67 dB
   • About 64 dB
6. 6.

   A speaker gives 60 dB at 10 m. About what level is it at 1 m, Ren?

   • About 80 dB
   • About 600 dB
   • About 70 dB
7. 7.

   A speaker gives 74 dB at 1 m. About what level is it at 2 m, Tala?

   • About 71 dB
   • About 37 dB
   • About 68 dB
8. 8.

   Two identical speakers each give 60 dB at a spot. About what level do they give together, Zee?

   • About 60 dB, the same
   • About 120 dB
   • About 63 dB
9. 9.

   Ten identical speakers each give 50 dB at a spot. About what level do they give together, Ari?

   • About 500 dB
   • About 53 dB
   • About 60 dB
10. 10.

    A spot gets 70 dB from one machine. A second, identical machine also gives 70 dB at that spot. About what is the total, Bo?

    • About 73 dB
    • About 140 dB
    • About 80 dB