Question

In YDSE if white light is used then

• A. except center, there will be spectrum
• B. except center, no spectrum anywhere
• C. spectrum every where
• D. spectrum at center only

Answer 1

Answer: (A)

White light is used, when at a particular point, condition for constructive interference may be satisfied only for some particular value of $\lambda$. Therefore, colour for this value of $\lambda$ will be visible at that point. Hence, interference fringes will be coloured. However, centre of coloured fringe will be white.