Lateral Shift Model

Five coloured rods stand behind a thick glass slab. Look at them through the slab at an angle and each rod appears to jump sideways, because light bends as it enters the glass and bends back as it leaves.

How it works

1. Look at the rods straight through the slab: they line up with the parts above it
2. Move your eye to one side and look again at an angle
3. The rods seen through the glass now appear shifted sideways from the parts above the slab

What students learn

• Light bends when it passes from air into glass and from glass back into air
• The ray that comes out of a parallel-sided slab is parallel to the ray that went in, but displaced
• The shift grows with the angle of viewing and with the thickness of the slab

Try these experiments

1. Find the viewing angle at which the shift first becomes visible
2. Compare the shift for a small angle and a large angle
3. Draw the ray diagram for refraction through a rectangular glass slab and mark the lateral shift

Curriculum fit

In the box

• 1 × Lateral Shift Model on a printed base
• Thick glass slab with five coloured rods behind it

Pairs well with

Ray Optics KitLAO-102Laser Optical TankLAO-109