Sample 1Medium
A string 1.5 m long is fixed at both ends and is drawn vibrating in a stationary wave with three loops: four nodes, including the two ends, and three antinodes. The speed of transverse waves on the string is 200 m/s. What is the frequency of this vibration?
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The answer is A.
Each loop is λ/2, so 3(λ/2) = 1.5 m and λ = 1 m. Then f = v/λ = 200 Hz.
- B.
400 Hz takes each loop as a full wavelength length of 0.5 m.
- C.
133 Hz uses λ = 1.5 m, the length of the string.
- D.
67 Hz is the fundamental (one loop), not the three-loop mode.
NCERT: Class 11 Physics, Chapter 14