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⚛️ Physics  ·  Waves  ·  NEET & JEE

Power transmitted per unit length by a wave on a string (amplitude A, frequency f, tension T, linear density mu):

Answer: 2*pi 2 *mu*f 2 *A 2 *sqrt(T/mu).

  • A 2*pi<sup>2</sup>*f<sup>2</sup>*A<sup>2</sup>*sqrt(mu*T)
  • B 2*pi<sup>2</sup>*f<sup>2</sup>*A<sup>2</sup>*T
  • C pi<sup>2</sup>*f<sup>2</sup>*A<sup>2</sup>*sqrt(T/mu)
  • D 2*pi<sup>2</sup>*mu*f<sup>2</sup>*A<sup>2</sup>*sqrt(T/mu)

Correct answer: D. 2*pi<sup>2</sup>*mu*f<sup>2</sup>*A<sup>2</sup>*sqrt(T/mu)

Explanation: Power = (1/2) mu omega<sup>2</sup> A<sup>2</sup> v = (1/2) mu (2pi f)<sup>2</sup> A<sup>2</sup> sqrt(T/mu) = 2*pi<sup>2</sup>*mu*f<sup>2</sup>*A<sup>2</sup>*sqrt(T/mu).

Standing Wave: Nodes and Antinodes (Open Pipe, 2nd Harmonic)nodenodenodeantinodeantinodeSolid and dashed lines show the string/air column at two instants - nodes never move

A standing wave forms from two identical waves travelling in opposite directions and interfering; nodes (always zero displacement) and antinodes (maximum displacement) stay fixed in place, unlike a travelling wave where the whole pattern moves.

Concept context

Wave types, superposition, standing waves, Doppler effect, and sound intensity.

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