The superposition takes place between two waves of frequency $f$ and amplitude $a$. The total intensity is directly proportional to 

Assertion: If two waves of same amplitude produce a resultant wave of same amplitude, then the phase difference between them will be $120°$.
Reason: The resultant amplitude of two waves is equal to vector sum of amplitudes treated as vectors.

Waxing and waning of sound is noticeable if waxing and waning repeats at an interval

Two tuning forks of frequencies $256 \mathrm{Hz} \text{and }258 \mathrm{Hz}$ are sounded together. The time interval between two consecutive maxima heard by an observer is

Two tuning forks have frequencies $380 \mathrm{Hz}\text{ and} 384 \mathrm{Hz}$, respectively. When they are sounded together, they produce maximum sound. How long will it take to hear the minimum sound?

When two sound waves are superimposed, beats are produced when they have _____.

Two sound waves with wavelengths $5.0\mathrm{m}$ and $5.5\mathrm{m}$ respectively, each propagate in a gas with velocity $330\mathrm{m}/\mathrm{s}.$ We expect the following number of beats per second 

Two waves $y_1=0.25 \sin 316t$ and $y_2=0.25\sin 310t$ are travelling in same direction. The number of beats produced per second will be