Beat Frequency and Persistence of Hearing – Rankers Physics
Topic: Waves
Subtopic: Sound Wave and its Characteristics

Beat Frequency and Persistence of Hearing

Assertion (A): When two vibrating tuning forks having frequencies \(240 \text{ Hz}\) and \(300 \text{ Hz}\) are held near each other, beats cannot be heard by us.
Reason (R): This is because beats cannot be distinctly heard due to the property of persistence of hearing.
 
(1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
(2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(3) (A) is true but (R) is false
(4) Both (A) and (R) are false

Solution:

The beat frequency is \(|240 - 300| = 60 text{ Hz}\) . For distinct beats to be heard, the beat frequency should be less than \(10 text{ Hz}\) . Thus, Assertion (A) is true. Persistence of hearing is not the reason for inability to hear distinct beats; it's the ear's inability to follow rapid amplitude changes. Thus, Reason (R) is false.

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