Question:medium

Fundamental frequency of a sonometer wire is \(n\). If the tension is made 3 times and length and diameter are also increased 3 times, what is the new frequency?

Show Hint

Frequency depends inversely on length and on square root of linear density.
Updated On: Apr 17, 2026
  • \( \frac{n}{3\sqrt{3}} \)
  • \( 3n \)
  • \( \sqrt{3}n \)
  • \( \frac{n}{\sqrt{3}} \)
Show Solution

The Correct Option is A

Solution and Explanation

Step 1: Understanding the Concept:
The frequency of a string depends on length, tension, and linear mass density. Linear mass density further depends on diameter and volume density.
Step 2: Key Formula or Approach:
\[ n = \frac{1}{2L} \sqrt{\frac{T}{m}} = \frac{1}{2L} \sqrt{\frac{T}{\rho \times A}} = \frac{1}{2L} \sqrt{\frac{T}{\rho \times \frac{\pi D^{2}}{4}}} \]
\[ n \propto \frac{1}{L \times D} \sqrt{T} \]
: Detailed Explanation:
Let \(n_{1} = n\).
New length \(L_{2} = 3L_{1}\).
New diameter \(D_{2} = 3D_{1}\).
New tension \(T_{2} = 3T_{1}\).
\[ n_{2} = n \times \frac{L_{1}}{L_{2}} \times \frac{D_{1}}{D_{2}} \times \sqrt{\frac{T_{2}}{T_{1}}} \]
\[ n_{2} = n \times \frac{1}{3} \times \frac{1}{3} \times \sqrt{3} \]
\[ n_{2} = n \times \frac{\sqrt{3}}{9} = \frac{n \sqrt{3}}{3 \times 3} = \frac{n}{3\sqrt{3}} \]
Step 3: Final Answer:
The new frequency is \(\frac{n}{3\sqrt{3}}\).
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