Question

Two sounds having same speed in a medium are having wavelengths 1.3 m and 3.9 m. A person listens to these sounds. What difference would the listener would feel?

• 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 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.