Node — string motionless
Antinode — maximum swing
This 2D simulator draws a string fixed at both ends and animates the standing-wave pattern y(x,t) = A sin(nπx/L) cos(ωt) for the selected harmonic number n. Nodes (motionless points) and antinodes (points of maximum swing) are marked at their exact positions, and the readout panel computes the wave speed v = √(T/μ), the frequency f_n = n·v/(2L), and the wavelength λ_n = 2L/n straight from the string length, tension and linear-density sliders.