Reflections

When a wave reaches a boundary of two media, some or all of the wave will bounce back into the first media You see waves bounce off a pier or boat and continue through the lake You see your reflection in a mirror – light from your body hits the mirror and bounces back to you

When all of the wave is reflected (as in a high quality mirror), it is known as totally reflected When some of the wave continues in the original media (a reflection on a lake surface, a water wave hitting a boat), only part of the wave bounces back and it is known as partially reflected

Angle of Reflection The angle of the reflection depends on the angle the light comes in Light coming in to a surface is known as the incident ray Light reflected is known as the reflected ray Just like in pool, the angle coming in is the same as the angle going out

Measuring the Angle The angle of the incident ray or reflected ray is measured in relation to a line perpendicular to the surface at the point of reflection This perpendicular line is known as the normal

Mirrored Surface Normal Incident Ray Reflected Ray

Mirrored Surface Normal Incident Ray Reflected Ray

You Try It! Complete the three diagrams in your notes Find the Normal and Reflected Ray in the first diagram Find the Normal and Reflected Ray in the second diagram Find the Normal and the Reflected Ray in the third diagram

Virtual Image A reflection looks like the same image, only behind the surface of the reflective material If the mirrored surface is flat, the virtual image will look the same as the real image being reflected Funhouse mirrors change your reflection by curving the mirrors and therefore changing what the virtual image looks like

Impact of Surface The smoothness of a surface will determine what happens to the light reflected Glass or a calm lake will give an image as a reflection because all of the light rays from the image bounce on the same path to your eye

When a lake gets rippled, the image reflected gets distorted This is because some of the light rays of the image are sent in other directions, not to your eye

Smooth LakeRough Lake

When a reflection is scattered due to the rough surface it bounces off, it is known as a diffuse reflection Sound waves can also be diffused by rough surfaces – this creates quieter sounds