An interference pattern was made by using red light. If the red light is replaced by blue light, the fringes will becomes
Options
(a) Wider
(b) Narrower
(c) Fainter
(d) Brighter
Correct Answer:
Narrower
Explanation:
Fringe width β = λD / d
β(ʀed) / β(ʙlue) = λ(ʀed) / λ(ʙlue)
λ(ʙlue) is < λ(ʀed)
Therefore, Fringe width with blue light < β with red light.
Fringes become narrower with blue light.