The figure on the left shows light bending toward the normal as it enters the denser medium of water.  Explain why the light bends in this direction using physical arguments rather than any equations.
	Which angle, θ2 measured in the water or θ1 measured in air, will be greater if the light bends toward the normal?
	Will a denser medium have a larger or a smaller index of refraction than a rarer medium?
	Use Snell's Law combined with your answer to the previous question to mathematically predict which angle will be greater when light moves into a denser medium.  How does this compare with your answer to the second question that was based on physical arguments?
	Use Snell's Law to predict what will happen to the light as it enters the water if it approaches the surface along the normal to the surface, as shown in the figure on the right.
	Now explain why this occurs using physical arguments rather than equations.

Hopefully you have decided that Snell's Law agrees with your physical intuition.  (If you are still unsure, you may click here to see a set of answers to these questions.)  Checking any calculations or expectations against what you expect based on physical arguments is a very good habit to develop.
 
 

Does light always travel into the next medium? Continue to the next page to find out!