Final answer:
The intensity of a sound wave is calculated using the formula I = (Δp)²/(2ρv). By substituting in the pressure amplitude, density of air, and speed of sound at the given temperature, we can find the intensity of the wave.
Step-by-step explanation:
The intensity of a sound wave can be calculated using the formula for the intensity of a plain wave, which is I = (Δp)²/(2ρvw). In this formula, Δp is the pressure amplitude, ρ is the density of the medium, and vw is the speed of sound in the medium. Given that the pressure amplitude (Δp) is 0.5 Pa, the density (ρ) of air at 0°C is 1.29 kg/m³ (which can be adjusted for 20°C if necessary), and considering the speed of sound (vw) in air at 0°C is 331 m/s (which increases slightly with temperature), we can plug these values into the formula to find the intensity.
Remember that the speed of sound varies slightly with temperature and can be adjusted using a temperature coefficient if a more precise answer is needed for specific temperatures like 20°C or 25°C. Without doing the calculation with specific values for 20°C, the given equation and values provide the general approach to calculating the intensity of a sound wave in air.