Grade 11 · Science · Physics

11th grade Sound intensity and the decibel scale worksheet

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Sound intensity and the decibel scale

Grade 11 Science Worksheet

NameDate

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

A sound has an intensity of 0.000002 W/m². What is its level, to 0.1 dB, Bo? Use I₀ = 10⁻¹² W/m².
A sound has an intensity of 0.00005 W/m². What is its level, to 0.1 dB, Esme? Use I₀ = 10⁻¹² W/m².
A sound has an intensity of 0.000009 W/m². What is its level, to 0.1 dB, Jun? Use I₀ = 10⁻¹² W/m².
4.
A listener moves from 2 m to 4 m from a small speaker. What happens to the intensity, Kira?
- It falls to a quarter
- It falls to an eighth
- It falls to a half
5.
A listener moves from 3 m to 1 m from a small speaker. What happens to the intensity, Luz?
- It becomes 6 times as intense
- It becomes 3 times as intense
- It becomes 9 times as intense
6.
The intensity 1 m from a speaker is 0.8 mW/m². What is it 4 m away, Milo?
- 3.2 mW/m²
- 0.05 mW/m²
- 0.2 mW/m²
7.
One sound is 5 times as intense as another. About how many decibels higher is it, by Pia's reading (OpenStax)?
- About 50 dB higher
- About 7 dB higher
- About 5 dB higher
8.
One sound is 1000 times as intense as another. How many decibels higher is it, Ren?
- 30 dB higher
- 1000 dB higher
- 3 dB higher
Read this first
Table, sound levels and intensities (OpenStax Table 17.2), with columns sound, level (dB) and intensity (W/m²)
Rustle of leaves, 10, 10⁻¹¹; whisper at 1 m, 20, 10⁻¹⁰; quiet home, 30, 10⁻⁹; normal conversation, 60, 10⁻⁶; busy traffic, 70, 10⁻⁵; loud radio, 80, 10⁻⁴.
9.
Using the table, a sound is 100 times as intense as a quiet home. What is its level, Zee?
- 130 dB
- 3,000 dB
- 50 dB
10.
Using the table, how does the intensity of busy traffic compare with normal conversation, Ari?
- 10 dB, so 10 W/m² more
- About 1.2 times as intense
- 10 times as intense

11th grade Sound intensity and the decibel scale worksheet – printable — Print: 1 2 3 4 5 6

About this worksheet

Sound intensity and the decibel scale. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

I can find intensity as power over area, I = P ÷ (4πr²), and use the inverse square law.
I can turn an intensity into decibels with β = 10 log₁₀(I ÷ I₀), and back again, with I₀ = 10⁻¹² W/m².
I can use decibel steps: ×10 is +10 dB, ×2 is about +3 dB, twice as far is about −6 dB, and two equal sources add about 3 dB.

Standard: none (IXL parity)

Words to know

intensity: Sound power through each square meter, in W/m²

decibel (dB): A level that counts factors of 10 in intensity

I₀: The threshold of hearing, 10⁻¹² W/m², which is 0 dB

inverse square law: Intensity falls as 1 ÷ r² from a small source

Common mistakes

Your child forgot to square the distance. Sound spreads over a sphere of area 4πr², so I = P ÷ (4πr²).

Your child left out the factor of 10. β = 10 log₁₀(I ÷ I₀), so multiply the logarithm by 10.

Your child left out the reference intensity. I = I₀ × 10^(β ÷ 10), with I₀ = 10⁻¹² W/m².

Questions parents ask

What is the most common mistake with sound intensity and the decibel scale?

Your child forgot to square the distance. Sound spreads over a sphere of area 4πr², so I = P ÷ (4πr²).

Are these 11th grade science worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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