The separation between a node and the next antinode in a vibrating air column is \(20\) cm. The speed of sound is \(320\) m/s. The frequency of sound is:
1. \(128\) Hz
2. \(256\) Hz
3. \(400\) Hz
4. \(800\) Hz
1. | \(2^{\text{nd}}\) harmonic | 2. | \(3^{\text{rd}}\) harmonic |
3. | \(6^{\text{th}}\) harmonic | 4. | \(12^{\text{th}}\) harmonic |
A string of length \(l\) is fixed at both ends and is vibrating in second harmonic. The amplitude at antinode is \(2\) mm. The amplitude of a particle at a distance \(l/8\) from the fixed end is:
1. \(2\sqrt2~\text{mm}\)
2. \(4~\text{mm}\)
3. \(\sqrt2~\text{mm}\)
4. \(2\sqrt3~\text{mm}\)
1. | \(420\) Hz | 2. | \(440\) Hz |
3. | \(484\) Hz | 4. | \(512\) Hz |