A wave is sent down a thick rope that is attached to a thinner rope. What happens when the wave reaches the junction? Explain in words, or draw a diagram.

A fraction of the wave will be reflected at the junction and the remainder will be transmitted through the junction into the thin rope

Explanation:

When the junction of the thin and the thick rope is reached by the wave, the wave behaves in the following two ways;

1) A fraction of the incident wave from the thick rope to the junction/boundary of the thin rope will be reflected back to in the direction of the thick rope with a lower amplitude and upright

2) A fraction of the incident wave from the thick rope to the junction/boundary of the thin rope will be transmitted through the thin rope such that the transmitted pulse on the thin rope will have an higher amplitude than that of the thick rope due to the available energy in the wave pulse and the lesser weight of the thin rope.