Question

Velocity of sound waves in air is 330 m/sec. For a particular sound in air, a path difference of 40 cm is equivalent to a phase difference of 1.6 p. The frequency of this wave is –

• A. 165 Hz
• B. 150 Hz
• C. 660 Hz
• D. 330 Hz

Answer 1

Answer: (C)

660 Hz

Answer 2

\begin{tabular} { r l | l } $\Delta \mathrm { x } = 40 \mathrm {~cm}$ & $\Delta \phi = \frac { 2 \pi } { \lambda } \Delta \mathrm { x }$ \ $\Delta \phi = 1.6 \pi$ & $\lambda = \frac { 2 \pi } { \Delta \phi } \times \Delta \mathrm { x }$ \ $\mathrm { V } = 330 \mathrm {~m} / \mathrm { s }$ & $= \frac { 2 \pi } { 1.6 \pi } \times \frac { 40 } { 100 }$ \ $\mathrm { n } = ?$ & $\lambda = \frac { 8 } { 16 } = \frac { 1 } { 2 } \mathrm {~m}$ \ $\mathrm {~V} = \mathrm { n } \lambda$ & \ $\mathrm { n } = \frac { \mathrm { V } } { \lambda } = \frac { 330 } { 1 / 2 }$ & \ $\mathrm { n } = 660 \mathrm {~Hz}$ & \end{tabular}