1. Tardigrade
  2. Question
  3. Physics
  4. A slit of width 'a' is illuminated by red light of wavelength 6500 mathringA. If the first diffraction minimum falls at 30 mathringA, then the value of ' a ' is

Question Error Report

Thank you for reporting, we will resolve it shortly

Back to Question

Q. A slit of width 'a' is illuminated by red light of wavelength $6500 \mathring{A}$. If the first diffraction minimum falls at $30 \mathring{A}$, then the value of ' $a$ ' is

KCETKCET 2021Wave Optics

Solution:

For diffraction minima
$a \sin \theta= n \lambda$
$n =1 $ for $ I$ minimum
$a =\frac{\lambda}{\sin \theta}=\frac{6.5 \times 10^{-7}}{\sin 30} $
$=\frac{6.5 \times 10^{-7}}{0.5} $
$=13 \times 10^{-7} $
$=1.3 \times 10^{-6} m$
$=1.3$ micron