The law of refraction says that

$$n_1\sin \theta_1=n_2\sin\theta_2$$

So we deduce that when $n_1<n_2$, we have $i_1>i_2$ and the refracted ray will be drawn closer from what is normal.

If we imagine a swimming pool, with an object half in it, we would be exactly in that case - the refracted ray will draw closer from the normal, and an observer would see the object further away than it really is.

However, I did a similar experiment, but the results were the opposite - see the below picture:

Picture of hand holding yellow pencil in sink filled with water such that the pencil is half-submerged. The pencil is held at a slight angle which appears to drastically increase underwater, such that the pencil looks bent upward. The shadow of the whole pencil appears completely straight in the background.

What am I not understanding here?


2 Answers 2


The apparent location of an object is where it would be if the light rays had traveled in a straight line from the object to your eyes. The rays actually bent downward at the water's surface, and came from a lower location. So the submerged object appears to be higher than it really is.


The law deals with the angles of incidence for the rays, not with the angles of the perceived image of the object.


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