MCQ
A slit of width a is illuminated by white light. For red light $(\lambda = 6500 \mathring A ),$ the first minima is obtained at $\theta = 30^\circ .$ Then the value of a will be
- A$3250 \mathring A$
- B$6.5 \times 10^{-4} \mathrm{~mm}$
- ✓$1.24$ microns
- D$2.6^{\times 10^{-4}} \mathrm{~cm}$
