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A string 2.0 m long, fixed at both ends, is driven by a 240 Hz vibrator and vibrates in its third harmonic mode. The wave speed and the fundamental frequency are

Asked in JEE Main 9th April 2nd Shift 2019 · Nodes, antinodes and harmonics

Answer: (2) 320 m s⁻¹, 80 Hz

Step-by-step solution

In the third harmonic L=3λ/2, so λ=(2×2.0)/3=4/3 m.

v=fλ=240×4/3=320 m s⁻¹, and the fundamental is (240)/3=80 Hz.

Why the other options are wrong

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