Question

which of the arrows measures the amplitude of the wave?

Explanation:

The amplitude of a wave is the maximum displacement from the equilibrium position. In the given diagram, arrow 2 measures the maximum displacement from the equilibrium (the horizontal axis) to the crest of the wave. Arrow 1 measures the wavelength (the distance between two consecutive similar points on the wave), and arrow 3 measures the distance from a trough to the equilibrium, but amplitude is specifically the maximum displacement (which is from equilibrium to crest or trough). However, typically amplitude is measured from the equilibrium to the crest (positive direction). Since arrow 2 is from equilibrium to crest, it represents the amplitude.

Answer:

2