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

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) =(\lambda)/(a)`

`sin (p) =(632.8* 10^(-9))/(1 * 10^(-3))`

`p =sin^(-1)(0.0006328)`

p = 0.0363° angle of the first dark ring