A microphone receiving a pure sound tone feeds an oscilloscope, producing a wave on its screen. If the sound intensity is originally 2.00 x 10-5 W/m2, but is turned up until the amplitude increases by 30.0%, what is the new intensity (W/m2) ?

The new intensity = 3.38 * 10⁻⁵ W/m²

Explanation:

Intensity of sound wave:

The intensity of sound is the rate of flow of flow of energy, per unit area, perpendicular to the direction of the sound wave.

Intensity (I) ∝ A²

where I = intensity, A = Amplitude.

∴ I₁/I₂ = A₁²/A²₂ ... equation 1

From the question, the amplitude increase by 30% of the initial

∴ A₂ = A₁ + 0.3A₁ = 1.3A₁, I₁ = 2.00*10⁻⁵ W/m²

∴ (2.00*10⁻⁵) / I₂ = A₁² / (1.3A₁) ²

(2.00*10⁻⁵) / I₂ = 1/1.3²

making I₂ the subject of the equation

I₂ = (2.00 * 10⁻⁵) * 1.3² = 3.38 * 10⁻⁵ W/m₂

The new intensity = 3.38 * 10⁻⁵ W/m²