Reflection or Refraction?

What a lovely picture of the sky reflected in a drop of water.

Except the sky isn’t actually reflected, it is refracted.

What is the difference between refraction and reflection?

Wikipedia states that reflection is…

 …the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated.

While refraction is…

 …the change in direction of a wave due to a change in its medium.

Refraction and Reflection
Refraction and Reflection – from Wikipedia

A mirror reflects light just like a sea wall reflects a water wave. The image above shows light that has entered a different medium – air to water.

The eye is a perfect example of this refraction. Remember when your biology teacher taught you that your eye perceives the world upside down? This is because the light changes medium when it enters the eye. Imagine the refracted ray coming in at many different angles as any image does as it enters your eye. This causes the image to flip as it enters the lens, outlined below.

Your brain does a very clever job switching it round for you. I wonder if the brain already knows this or if it is learned? Perhaps babies perceive the world as upside down until it’s brain catches up with it.

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