Answer:
Because nothing is blocking the LIGHT!
Explanation:
Light may still be shining on the whole glass but if it wasn't there light would shine brighter than if it was there.
All you can say about it is that it then vibrates perpendicular to the x-axis. But that could be up and down parallel to the y-axis, in and out parallel to the z-axis, or some of it in every possible direction perpendicular to the x-axis. We "polarize" the light when we want to pick out only one perpendicular direction and stop all the others.
Is the Frog Toy a piece of literature? If so, the type of wave is the "Wave of Life." Spring brings new life and a new start from the harsh winter.