Notice the size of the bubble. Observe the position of the bubble. When you have finished observing the bubbles, dispose of the mixture in the glass dish by rinsing it down the drain with water. The colors of a soap bubble come from reflections of the white light that falls on the bubble. White light, such as from the sun or from a light bulb, contains light of all colors.
Light has waves, and the length of the wave, from crest to crest, determines the color of the light.
When light reflects from a bubble, some of each wave reflects at the outside surface of the soap film. Some light travels through the soap film, and reflects from the inside surface of the film. Interference between waves occurs whenever waves travel through the same space. Interference occurs when two rocks are tossed near each other into a lake. Circular waves on the surface of the water spread out from where each rock entered the water.