Two tuning forks `A` and `B` produce `6` beats per second. Frequency of `A` is `300 H_(Z)` . When `B` is slightly loaded with wax, beat frequency decreases . Find original frequency of `B` .

Explanation

Since, `A` and `B` produce `6` beats per second. Therfore, oringinal frequency of `B` may be `306 H_(Z)` or `294 h_(Z)` .
When `B` is loaded with wax, its frequency will decrease (suppose it decreases by `1 H_(Z)` . ) So, if it is `306 H_(Z)` . If it is `294 H_(Z)`, it will become `293 H_(Z)` .
frequency of `A` is unchanged `(=300 H_(Z))` . If `f_(B)` become `305 H_(Z)` . then beat frequency will become `5 H_(Z)` . If `f_(B)` become `293 H_(Z)` , then it will it become `7 H_(Z)` . But in the question it is given that beat frequency haas decreased . So, the correct answer is `306 H_(z)` .