Question

Two sounds having the same speed in a medium are having wavelengths 1.3 m and 3.9 m. A person listens to these sounds. What is the difference between the two sounds the person hears?

• A. First sound is heard with higher pitch
• B. First sound is heard with better quality
• C. First sound is louder
• D. Second sound is heard with higher pitch

Answer 1

The correct option is A

First sound is heard with higher pitch

Since velocity (v) is the product of frequency (f) and wavelength (w),
$f_1$ = $\frac{v}{w_1}$ = $\frac{v}{1.3}$ = $\frac{10v}{13}$ = $\frac{30v}{39}$
$f_2$ = $\frac{v}{w_2}$ = $\frac{v}{3.9}$ = $\frac{10v}{39}$
Now, $\frac{f_1}{f_2}$ = $\frac{\frac{30v}{39}}{\frac{10v}{39}}$ = 3
As $f_1$ is 3 times greater than $f_2$, first sound has higher pitch than the second one, because higher the frequency, higher is the pitch.