Ruler in Water
Purpose
A meter stick in water appears bent at the surface, providing a visual introduction to refraction and Snell's Law. Students see that the apparent displacement arises from light bending at the water-air interface.
Figure 1:
The ruler appears discontinuous and bent at the water surface due to refraction, as light rays change direction when transitioning between water (n ≈ 1.33) and air (n ≈ 1.00).