Why the soap bubble or petrol on water give a color full spectrum ?
Soap bubble or petrol on water give a color full spectrum because of interference of light. Each color of light has a different wavelength hence a disparity in the path of light will cause constructive interference of certain colors whereas other color will not be observed because of destructive interference. Because the oil film gradually thins from its center to its periphery, different bands of the oil slick produce different colors.