Sitting outside with my back to the sun, I noticed that the shadow cast by each clear lens of my glasses was equally as dark as that cast by the frame and my head. Why? Surely the clear lens would let the light through rather than casting a shadow?
• The purpose of each lens in the spectacles is to bend the light rays passing through it, and assist the wearer in focusing clearly. This may also mean that light passing through the lenses is bent away from the area where the shadow forms, and this is as effective at…
