Vibrating string loop sim
Drag through 8 modes of a closed loop: whole waves fit round it, and f = n v / C climbs 105 Hz at a time.
Waves: standing waves (an analogy for string theory) · covers the A-Level, IB, University intro topic
What the sim shows
A free loop of string rings steadily when a whole number of waves fits round it: n wavelengths = the loop's length. Held at one point, as here, it can also ring with half-waves (f = m v / 2C); this figure shows the whole-wave modes. Waves travel along this string at v = √(T/μ) = √(40 N ÷ 0.010 kg/m) = 63 m/s, so mode n rings at f = n v / C ≈ 105.4 Hz × n. More waves round the loop means a higher frequency, and more energy for the same size of wobble. The motion is shown slowed down and its height exaggerated. This is an ideal string: a stiff wire loop rings at different frequencies, because its stiffness resists bending as well as the tension pulling it straight. String theory borrows this picture. It proposes that every particle is a tiny vibrating string (a closed loop or an open strand), perhaps around 10⁻³⁵ m long (no one knows the true size), and that the way it vibrates decides which particle it is, how heavy it is and what charge it has. Real strings in the theory move in extra dimensions, so this loop is only a loose picture. Its predictions are far beyond today's experiments, so it has not been tested or confirmed.
- Nodes: points of the loop that never move (2 for every wave)
- Loop of string, 60 cm round, under 40 N tension
- Dashed: where the loop rests when it is still
Use it in your lessons
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