Physics Form 5: Chapter 1 - Shape of the Coastline due to Wave Refraction

• In the centre of the ocean, the wavefronts are straight and parallel to each other. This is because the water waves travel at uniform speed as the depth of the sea water is uniform.
• When the waves reach the coast, the water is shallower.
• Wave speed is reduced and refraction occurs. The wavefronts are refracted and become closer to each other. Wavelength decreases.  
• Refraction causes the wavefronts to be bent towards the normal.

• Wave refraction causes wavefronts to parallel the shape of the coastline as they approach shore.
• Wave refraction also causes wave energy to converge at cape and resulting erosion.
• Wave energy diverges at bay and spreads out to a wider region, resulting deposition of sand. Therefore, amplitude of waves at the bay is smaller than at the cape.