This makes spearfishing very difficult! Apparent Depth When viewed from another medium, objects appear to have a different depth than they actually do. This makes spearfishing very difficult!

The photographs show a bathroom basin. In Figure 1 the basin is empty. In Figure 2 the basin is full of water. Both photographs were taken from the same position. Photograph 1 Photograph 2 In photo 2 the plug is visible and the basin appears shallow compared to photo 1

empty basin full basin normals camera camera Explain in detail (and with the help of diagrams) why an image of the plug can only be seen by the camera when the sink is filled up with clear water.

Refraction of light at an interface Water and air are the two mediums empty basin camera Light ray to camera is blocked when sink is empty full basin normals camera Refraction of light at an interface Water and air are the two mediums The empty basin’s edge blocks the view of the plug. When the basin is full of water the light rays from the plug bend away from the normal at the water/air interface. The rays bend towards the camera (away from the normal) so the plug can be viewed.

normal nair = 1.05 The photo shows the plug in a bathroom basin. The basin is full of water. The diagram shows how the light is refracted. The angle of incidence is 370 The angle of refraction is 500 Calculate the refractive index of the water. normal nair = 1.05

The angle of incidence is 370 The angle of refraction is 500 Calculate the refractive index of the water. nair = 1.05 normal 50o 37o

Because of atmospheric refraction, we have lingering, elliptical sunsets. Sun Earth Sun

The boundary from one medium to another is definitive. The boundary from one medium to another is a gradient.

Our eyes perceive the blue sky and can mistake it for water. Mirages The warm air has a lower density (larger n –moves slower) and so light totally internal reflects before hitting the ground. Our eyes perceive the blue sky and can mistake it for water.