Question

A thin layer of oil floats on a water puddle. An observer sees a colored pattern. This happens because?

1) two surfaces each transmit some light and reflect some light.
2) oil always does this, even if it is not on water.
3) water transmits light and never reflects light.
4) sunlight's frequency range shifts to infrared at the boundary of water and oil.

Answer 1

The colored pattern observed on an oil slick floating on water is caused by thin film interference, where light reflected from different surfaces of the thin film interfere with each other, resulting in different colors being reflected.

Step-by-step explanation:

The bright colors seen in an oil slick floating on water are caused by interference, specifically thin film interference. This is when light reflected from different surfaces of a thin film interfere with each other. The interference creates constructive and destructive interference patterns, resulting in different colors being reflected.

When light strikes the thin layer of oil on the water, some of it is transmitted through the oil and some is reflected. The reflected light waves interfere with each other, and depending on the thickness of the oil layer, certain wavelengths of light are enhanced and others are suppressed. This creates the colored pattern observed by the observer.