Question

If a laser beam is red with a wavelength of 632.8 nm, what is the angle from the center of the airy disk to the first dark ring?

Answer 1

Answer

given,

wavelength of laser light = 632.8 nm

assuming that aperture of lens be equal to dia = 1 mm

now,

When laser light passes through aperture diffraction of light takes place

The first diffraction minima occurs at

        $a sin (p) =\lambda$

where a is the width of aperture

λ is the wavelength of light

p is the angle

        $sin (p) =\dfrac{\lambda}{a}$

        $sin (p) =\dfrac{632.8\times 10^{-9}}{1 \times 10^{-3}}$

        $p =sin^{-1}(0.0006328)$

               p = 0.0363° angle of the first dark ring