Four tuning forks of frequencies $200 \, Hz, 201 \, Hz, 204 \, Hz$ and $206 \, Hz$ are sounded together. The beat frequency will be

$A$ wire having tension $225 \ N$ produces six beats per second when it vibrates with a tuning fork. When the tension changes to $256 \ N$,it vibrates with the same fork,and the number of beats per second remains unchanged. The frequency of the fork is: (in $Hz$)

$A$ 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 tuning forks $A$ and $B$ produce notes of frequencies $258 \,Hz$ and $262 \,Hz$. An unknown note sounded with $A$ produces certain beats. When the same note is sounded with $B$, the beat frequency gets doubled. The unknown frequency is (in $\,Hz$)

Two tuning forks $A$ and $B$ sounded together give $6$ beats per second. With an air resonance tube closed at one end,the two forks give resonance when the two air columns are $24 \, cm$ and $25 \, cm$ respectively. Calculate the frequencies of the forks.

What is beat frequency?