Question

What is the path difference between rays from the top and middle of a slit of width \[a\]?

Options

• \[2a\sin\theta\]

• \[a\sin\theta\]

• \[\frac{\lambda}{2}\sin\theta\]

• \[\frac{a}{2}\sin\theta\]

Answer 1

The top and middle of the slit are separated by half the slit width, \[\frac{a}{2}\]. Their path difference in the direction at angle \[\theta\] is \[\frac{a}{2}\sin\theta\].