as the object is inside a bag which contains air in it , and water sorrounds the bag, this causes light to travel from an optically denser to a rarer medium, which causes total internal reflection , and the light rays just bounce off ofthe bag
Well as you can see that the color doesn't actually disappears. The light which is reflected to bent. Which is that when incident ray travels from air(low refractive index) to water(high refractive index), the object bends. Here the ray bends too. So it's all about refraction. (Could be wrong but basic concept is this)
This called refraction of light basically it means when light enters from one medium to other medium it changes it direction in the others terms it is the bending of light ray
This experiment will depend heavily on the curvature of the glass you conduct it in - that will change where the light refracts. I recommend trying different vases :) And moving your paper left/right, up/down across different axes :)
I recommend trying different size vases - I've noticed that the curvature of the vase can change when the image disappears (it effects the refraction), and rotate your image left and right as well as up and down
It's not a scared so good like you need to like do it properly not from the down don't you see from the down the colour is there from the up it's a complete pass I have tried it this is like so good
