Petrine sends one ray at 40° from the normal toward two tanks: one of water, one filled by a glass block. The ray bends in both. In the glass it bends more.
Before any law or arithmetic, you can rank bends. This lesson gives the comparison rule.
Both media slow the light, so both bend the ray toward the normal.
But they slow it by different amounts. Glass slows light more than water does.
So the same 40° ray bends more on entering the glass than on entering the water. The drawn angles show it: 25° from the normal in the glass, 29° in the water.
The index of refraction ranks media for you: a larger n means a slower medium, so a larger n means a larger bend for the same incoming ray.
The comparison needs no calculation. Rank the media by how much they slow light, and you have ranked the bends.
The rule reads the other way too. If the same incoming ray bends more in one medium, that medium slows light more: it is the optically denser one.
The same ray of sunlight enters water in one test and glycerin in another, at the same angle. Light travels more slowly in glycerin than in water. In which test does the ray bend more?
The comparison rule: crossing into the medium that slows the light more causes a larger change in direction.
Glycerin slows the light more than water does.
The incoming ray and angle are the same in both tests.
The ray bends more in the glycerin test.
One ray enters two gemstones at the same angle. In the first stone it bends more than in the second. Which stone slows light more?
A larger bend for the same incoming ray marks the medium that slows light more.
The first stone bent the ray more.
The first stone slows light more: it is the optically denser stone.
One ray enters water in one test and a diamond in another, at the same angle. Light travels more slowly in diamond than in water. In which test does the ray bend more?
The same ray enters a sapphire (n = 1.77) in one test and a block of ice (n = 1.31) in another, at the same angle. In which test does it bend more?
Nilo says: 'Two media can both bend the same incoming ray toward the normal, and still bend it by different amounts.' Is Nilo correct?
The same ray of light enters water in one test and glycerin in another, at the same angle. Light travels more slowly in glycerin than in water. Which statement is true?
A ray of light enters a honey sample and a vinegar sample at the same angle, in two tests. The bend is clearly larger in the honey. What does this show?
The same ray arrives at 45° from the normal at an ice surface (n = 1.31) in one test and at a window-glass surface (n = 1.52) in another. In which test is the angle between the refracted ray and the normal smaller?