Question

A diffraction is obtained by using a beam of red light. What will happen if the red light is replaced by the blue light

• A. Bands will narrower and crowd
  full together
• B. Bands become broader and further apart
• C. No change will take place
• D. Bands disappear

Answer 1

The correct option is A Bands will narrower and crowd

full together

We know that the fringe width $\propto \lambda$,

$\because {\lambda }_{blue}<{\lambda }_{red}$,

hence for blue light the diffraction bands becomes narrow and crowded together.