The 4:1 pendula demonstration involves two pendulums with lengths in a 4:1 ratio. This setup shows that the period of a pendulum is proportional to the square root of its length. As a result, the pendulum with the longer length will have a period twice that of the shorter one, illustrating the relationship T ∝ sqrt(L)​. This experiment helps students understand how changing the length of the pendulum affects its oscillation period, reinforcing the principles of harmonic motion.