Why a spoon looks bent in water: try it yourself

Make the apparent bend appear

Put a spoon at an angle in a half-full glass of water: its handle can suddenly look bent or displaced at the waterline. This before-and-after experiment lets you see light refraction with everyday objects.

1. Get a clear, smooth-sided glass, water and a spoon with a straight handle.
2. Look at the handle outside the glass first.
3. Half-fill the glass and place the spoon in it at an angle.
4. Look from the side, obliquely towards the waterline. Move your head slightly upwards and sideways until you notice the offset.
5. Lift the spoon out: its handle is still straight.

Why your eyes place it elsewhere

Light from the submerged part changes direction as it passes between water and air. Your visual system interprets the incoming rays as if they had travelled in straight lines. That makes the underwater part appear in a different position from the part above the surface. The metal has not bent; the light's path has changed.

If the effect is hard to see

Change your viewing angle first, rather than bending the spoon. The water level and the shape of the glass affect how obvious the apparent bend is. Strongly curved or patterned glass can add distortions of its own.

You are observing an optical effect, not a physical change to the spoon. Compare several viewpoints while leaving the spoon still: the visible offset can change even though the object does not move.