Two wires are producing fundamental notes of the same frequency. Change in which of the following factors of one wire will not produce beats between them?

$A$ tuning fork $A$ produces $5$ beats per second with a tuning fork of frequency $480 \ Hz$. When a little wax is stuck to a prong of fork $A$,the number of beats heard per second becomes $2$. What is the frequency of tuning fork $A$ before the wax is stuck to it (in $Hz$)?

Two waves of lengths $50 \; cm$ and $51 \; cm$ produce $12$ beats per second. The velocity of sound is .... $m/s$.

$A$ prong of a vibrating tuning fork is in contact with the water surface. It produces concentric circular waves on the surface of the water. The distance between five consecutive crests is $0.8 \ m$ and the velocity of the wave on the water surface is $56 \ m/s$. The frequency of the tuning fork is: (in $Hz$)

Two vibrating tuning forks produce progressive waves given by $y_1 = 4 \sin(500 \pi t)$ and $y_2 = 2 \sin(506 \pi t)$. These tuning forks are held near the ear of a person. The person will hear

The correct figure that shows,schematically,the wave pattern produced by the superposition of two waves of frequencies $9\,Hz$ and $11\,Hz$ is: