As light travels through a fiber optic cable, amplitude measures how far each wave moves from its resting point. When the cable bends tightly, some light escapes through the walls instead of bouncing forward — and that loss shows up directly as a drop in amplitude. You wrap the cable around wooden dowels ranging from 1 inch to 1/8 inch in diameter and record the amplitude at each bend using a scopemeter. Tighter bends produce greater amplitude loss. Frequency stays constant throughout, confirming that the bends affect wave height, not wave rate.