Question

Two tones of frequencies n₁ and n₂ are sounded together. The beats can be heard distinctly when 

(a) 10 < (n₁ – n₂) < 20 

(b) 5 < (n₁ – n₂) > 20 

(c) 5 < (n₁ – n₂) < 20 

(d) 0 < (n₁ – n₂) < 10

Answer 1

Correct option: (d) 0 < (n₁ – n₂) < 10

Explanation: 

As number of beats/sec = diff. in frequencies has to be less than 10, therefore 0 < (n₁ – n₂) < 10