Assertion : A white source of light during interference forms only white and black fringes. Reason : Width of fringe is inversely proportional to the wavelength of the light used.

Step-by-step solution

Fringe width ( = D d ). This depends on the wavelength. Diffraction depends on the wavelength of light. Therefore if a white source of light is used, only the central fringe will be white. All the rest have different wavelengths and some orders will also overlap for different colours.