A soap bubble is essentially a thin film of water surrounded by air. The colors you see in soap bubbles are produced by interference. What visible wavelengths of light are strongly reflected from a 390-nm-thick soap bubble? What color would such a soap bubble appear to be?
Wavelength spectrum of visible light for the range of 390nm to 460nm is seen as violet. So the violet colour will be seen and reflected as what the eyes will see
