Question

What will happen to the light at the third maxima on both sides of the zeroth fringe in a Young's double slit experiment ?

• A. Travels the same distance
• B. From the lower opening travels three times farther than light from the upper opening
• C. From the upper opening travels three times farther than light from the lower opening
• D. From either opening travels 2 wavelengths farther than light from the other opening
• E. From either opening travels 3 wavelengths farther than light from the other opening

Answer 1

Answer: (E)

From either opening travels 3 wavelengths farther than light from the other opening

For constructive interference in Young's double slit experiment , path difference between two light waves from two openings is given by $\Delta x=n\lambda$ where $n=0,1,2,\mathrm{3.....}$

for third maxima $n=3$,

and $\Delta x=3\lambda$

therefore we can say that light from either opening travels farther than light from other opening.