When a drop of oil spreads across a water surface, it exhibits beautiful colours in daylight due to

Step-by-step solution

When a drop of oil spreads across a water surface, it forms a thin film. When white light from the sun falls on this thin film, a portion of the light is reflected from the upper surface of the oil film and another portion is reflected from the lower surface (oil-water interface). These two reflected light waves superimpose and interfere with each other. The condition for constructive or destructive interference depends on the thickness of the film and the wavelength of the light. Since white light consists of diff