Question

769Hz longitudinal wave in air has a speed of 344m/s. At a particular instant, what is the phase difference (in degrees) between two points 5.0 cm apart?

• A. 30
• B. 40
• C. 45
• D. 60

Answer 1

The correct option is B 40

Given that,

The frequency of wave is $\nu =769Hz$

The speed of wave is $v=344m{s}^{-1}$

The wavelength of wave is given by

$\lambda =\frac{v}{\nu }$

$\lambda =\frac{344}{769}$

$\lambda =0.447m=44.7cm$

Hence, the phase difference between two points 5.0 cm apart is

$\frac{5}{44.7}\times {360}^{\circ }=0.1118\times {360}^{\circ }={40.24}^{\circ }\approx {40}^{\circ }$