JEE Mains · Physics · STD 11 - 14. waves and sound
A string \(2.0\, m\) long and fixed at its end is driven by a \(240\, Hz\) vibrator. The string vibrates in its third harmonic mode. The speed of the wave and its fundamental frequency is
- A \(320\, m/s, 120\, Hz\)
- B \(180\, m/s, 80\, Hz\)
- C \(180\, m/s, 120\, Hz\)
- D \(320\, m/s, 80\, Hz\)
Answer & Solution
Correct Answer
(D) \(320\, m/s, 80\, Hz\)
Step-by-step Solution
Detailed explanation
We have: \(f=\frac{n v}{2 \ell}\) \(240=\frac{3 \times v}{2 \times 2}\) \(\Rightarrow \quad v=320 \mathrm{m} / \mathrm{s}\) Fundamental frequency \(=\frac{v}{2 \ell}=80 \mathrm{Hz}\)
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