Soap film appears coloured because:

Question

Question

Answer 1

CONCEPT:

Property	Definition
Dispersion	The splitting of a composite beam of light into its constituent colours is called dispersion of light. The dispersion of white light occurs because the colours of white light travel at different speeds through the glass prism.
Refraction	The bending of a ray of light when it goes from one medium to another is called refraction of light. When light enters from rarer to a denser medium it bends towards the normal to the interface of the media. Similarly, when light travels from a denser to the rarer medium it bends away from the normal.
Total internal refraction	Total internal reflection (TIR) of light is the reflection of light within the same medium when a ray of light is incident at the interface of two medium at an angle of incidence which is greater than the critical angle for the pair of media i.e. i > ic
Interference	When two light sources from different coherent sources meet together, then there is a distribution of energy is disturbed by each other this superposition of two light waves is called Interference of light waves.

EXPLANATION:

Soap film looks colourful in white light because of the interference of light by reflecting off the front and back surfaces of the thin soap film. Therefore option 2 is correct.