Question

The tension in a wire is decreased by 19%, then the percentage decrease in frequency will be……… 

(A) 19% 

(B) 10% 

(C) 0.19% 

(D) None of these

Answer 1

The correct option (B) 10%

Explanation:

f ∝ √T

(f₁/f₂) = √(T₁/T₂)

given: T₂ = 81% T₁ as T₁ is decreased by 19%

∴ (f₁/f₂)  = √{(T₁)/(0.81 T₁)}

∴ (f₁/f₂)   = √{(100)/81} = (10/9)

(f₂/f₁) = (9/10)

∴ f₁ – (f₂/f₁) = 1 – (9/10)

∴ {(f₁ – f₂)/f₁} = (1/10)

∴ % decrease in frequency = (1/10) × 100

= 10%