The main factor which affects the speed of sound wave is the?

Analysis

The question asks us to identify the primary factor that determines how fast a sound wave travels through space. We need to look at the physical characteristics of sound propagation.

Concept Explanation

Sound is a mechanical wave, meaning it requires a material medium (like air, water, or steel) to travel. The speed of sound ($v$) is determined by the physical properties of that medium, specifically its elasticity (or bulk modulus) and its density.

The formula for the speed of sound in a medium is generally given by:

Where:

• $E$ is the elastic property of the medium (how easily it returns to its shape after being compressed).
• $\rho$ (rho) is the density of the medium.

Because sound waves rely on the vibration of particles to transfer energy, the "stiffness" and "density" of the particles dictate how quickly that energy is passed along. Factors like amplitude, intensity, and loudness are characteristics of the sound wave itself, but they do not change the speed at which the wave moves through a specific medium.

Step-by-Step Solution

1. Evaluate Option B (Amplitude): Amplitude relates to the energy or volume of the sound, not the speed.
2. Evaluate Option C (Intensity): Intensity is the power per unit area; it describes how "strong" the sound is, not its speed.
3. Evaluate Option D (Loudness): Loudness is a subjective human perception of intensity. It does not affect the physical speed of the wave.
4. Evaluate Option A (Properties of the medium): As shown in the formula $v = \sqrt{E/\rho}$, the speed is entirely dependent on the medium's elasticity and density. For example, sound travels faster in steel (high elasticity) than in air (low elasticity).

Conclusion

The speed of sound is independent of the wave's characteristics (like loudness or amplitude) and is strictly a function of the medium through which it travels. Therefore, the properties of the medium are the main factor.

Exam Tip

Remember the acronym "MED": Medium Effects Determine speed. If you are ever asked what affects the speed of a wave, always look for the medium's properties (temperature, density, elasticity) rather than the wave's features (frequency, amplitude, wavelength).