If a wavelength measurement is expressed in feet per cycle and the value increases while the speed of sound remains constant, what happens to the wavelength?

If a wavelength measurement is expressed in feet per cycle and the value increases while the speed of sound remains constant, what happens to the wavelength?

• A. Higher frequency
• B. Greater velocity
• C. Longer wavelength
• D. More energy

Answer: (C)

The key idea is the relationship among speed, wavelength, and frequency: v = f × λ. If the speed of sound is fixed and the wavelength (the distance per cycle) increases, the frequency must decrease to keep the product the same. So the wave stretches out in space, giving a longer wavelength. A higher frequency would require a shorter wavelength at the same speed, which isn’t happening here. Energy isn’t directly determined by this change in wavelength alone, so it isn’t the correct consequence.

The key idea is the relationship among speed, wavelength, and frequency: v = f × λ. If the speed of sound is fixed and the wavelength (the distance per cycle) increases, the frequency must decrease to keep the product the same. So the wave stretches out in space, giving a longer wavelength. A higher frequency would require a shorter wavelength at the same speed, which isn’t happening here. Energy isn’t directly determined by this change in wavelength alone, so it isn’t the correct consequence.