A string under a tension of 129.6 N produces 10 beats per sec when is ...
As here the tension in the wire in charged, so its fundamental frequency

Now with increase in tension, K√T will increase and beats and decreasing to zero when T = 160 N (as unison means the frequencies are equal).

Substituting the value of K from second equation in first,

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A string under a tension of 129.6 N produces 10 beats per sec when is ...
As here the tension in the wire in charged, so its fundamental frequency

Now with increase in tension, K√T will increase and beats and decreasing to zero when T = 160 N (as unison means the frequencies are equal).

Substituting the value of K from second equation in first,

A string under a tension of 129.6 N produces 10 beats per sec when is ...
Understanding the Problem
The problem involves a string under tension producing different frequencies when the tension is varied. When the tension is 129.6 N, the string produces 10 beats per second, and when the tension is increased to 160 N, it sounds in unison with a tuning fork.
Key Formulas
- The frequency of a vibrating string is given by the formula:
Frequency (f) = (1/2L) * √(T/μ)
Where:
- T = tension in the string
- μ = linear mass density of the string
- L = length of the string
Calculating Frequencies
1. Initial Tension (129.6 N)
- The string produces 10 beats per second, meaning its frequency (f1) is 10 Hz away from the tuning fork's frequency (f). Thus, we have:
f1 = f ± 10
2. Increased Tension (160 N)
- At this tension, the string resonates in unison with the tuning fork, meaning:
f2 = f
Finding the Relation Between Frequencies
- As the tension increases, the frequency of the string also increases.
- The ratio of the square roots of the tensions gives us the relationship between the frequencies:
f2/f1 = √(T2/T1)
- Substituting T1 = 129.6 N and T2 = 160 N:
f2/f1 = √(160/129.6)
Calculation Steps
- Since f2 = f and f1 = f ± 10, we can infer that:
f2 = f1 + 10 or f1 - 10
- Solving these equations will lead you to find that:
f2 = 100 Hz.
Conclusion
The fundamental frequency of the tuning fork is therefore 100 Hz, confirming that option 'B' is correct.