A slit of width 'a' is illuminated by red light of wavelengt... | Physics | SolveeIt

Question

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

$6.5 \times 10^{-4} mm$

$1.3$ micron

$3250 ?$

$2.6 \times 10^{-4} cm$

Answer

$1.3$ micron

Explanation

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

Physics Question on Refraction of Light

Solution