What does refraction cause waves to do

If the ray meets the boundary at an angle to the normal , it bends towards the normal. The reverse is also true. A light ray speeds up as it passes from glass into air, and bends away from the normal by the same angle.

For a given frequency of light, the wavelength is proportional to the wave speed:. So if a wave slows down, its wavelength will decrease. The effect of this can be shown using wave front diagrams, like the one below. The first student reached the tape, slowed down, and observed the rest of the students marching ahead at the original speed.

The change in direction of the line of students only occurs at the boundary when the students change speed and approach at an angle. The Marching Soldiers analogy provides an excellent analogy to understanding the cause of light refraction. The line of students approaching the masking tape are analogous to a wavefront of light.

The masking tape is analogous to a boundary between two media. The change in speed that occurred for the line of students would also occur for a wave of light. And like the marching students, a light wave will not undergo refraction if it approaches the boundary in a direction that is perpendicular to it. The same two conditions that are necessary for bending the path of the line of students are also necessary for bending the direction of a light ray.

Light refracts at a boundary because of a change in speed. There is a distinct cause-effect relationship. The change in speed is the cause and the change in direction refraction is the effect. Physics Tutorial. My Cart Subscription Selection. Student Extras. The rays are bent towards the normal.

At the second interface from glass into air the light passing into the air is refracted again. The rays are now bent away from the normal. Reflectance and transmittance At a boundary between two transparent media, light is partially reflected and partially refracted. The ratio of the reflected intensity to the incident intensity is called the reflectance R and the ratio of the transmitted intensity to the incident intensity is called the transmittance T.

We distinguish between p-polarization and s-polarization. Let the plane of incidence contain the normal to the boundary and the incident wave vector k 1. The electric field vector E 1 is perpendicular to k 1. E p lies in the xz-plane and E s is perpendicular to the xz-plane, i. The electric field of the incident light is a linear superposition of p- and s-polarized fields. Waves breaking at an angle on some areas of the the beach would thus lead to the removal of sediment by longshore drift.

Coastal defence rock islands and wave refraction The impact of the rock islets at Sitges: refraction has led to beach erosion Sitges Coastal Management. Make Your Booking.