Refraction in the bathroom

 

There was an innovative fix to support the old tap mechanism. Look above for how wide the block actually is.

Now look from the new angle and look at how thin the block appears. This is because the light goes much slower in the glass and so bends considerably when it leaves the glass and comes out into the air to meet my eye. My brain knows light travels in straight lines and projects a straight path, which would result in a thinner looking block. When viewed from straight on, refractive index can be calculated by doing real depth/apparent depth.