Class 12PhysicsWave OpticsFresnel distance, Diffraction through circular slit, concept of Airy Disc, Rayleigh Criterion of Resolution , Fraunhofer diffraction
MediumWhat is Fresnel distance? Write its formula.
(N/A) The Fresnel distance is defined as the distance from a slit or aperture at which the spreading of light due to diffraction becomes comparable to the size of the aperture itself.
Beyond this distance,the ray optics approximation (rectilinear propagation of light) is no longer valid,and diffraction effects become significant.
It acts as a limit to the validity of ray optics.
The formula for Fresnel distance $(z_F)$ is given by:
$z_F = \frac{a^2}{\lambda}$
Where:
$a$ = size of the aperture or slit width
$\lambda$ = wavelength of the light used
Beyond this distance,the ray optics approximation (rectilinear propagation of light) is no longer valid,and diffraction effects become significant.
It acts as a limit to the validity of ray optics.
The formula for Fresnel distance $(z_F)$ is given by:
$z_F = \frac{a^2}{\lambda}$
Where:
$a$ = size of the aperture or slit width
$\lambda$ = wavelength of the light used
Explore More
Similar Questions
The limit of resolution of a telescope and a microscope is imposed because of which phenomenon?
Easy
View SolutionIn the Fraunhofer diffraction experiment, $L$ is the distance between the screen and the obstacle, $b$ is the size of the obstacle, and $\lambda$ is the wavelength of the incident light. The general condition for the applicability of Fraunhofer diffraction is:
For what distance is ray optics a good approximation when the aperture is $3\; mm$ wide and the wavelength is $500\; nm$?
Easy
View SolutionIn a Fraunhofer diffraction pattern,the slit width is $0.2 \ mm$ and the screen is at $2 \ m$ away from the lens. If the distance between the first minimum on either side of the central maximum is $1 \ cm$,the wavelength of light used is: (in $Å$)
Explain that for a greater distance,the spreading due to diffraction dominates over that due to ray optics. $OR$ Explain the importance of Fresnel distance.
Medium
View SolutionVedclass Products
For Students
Vedclass Test Series
Mock tests in real JEE/NEET style with performance analysis. 5-day free trial.
Start Free TrialFor Teachers
Exam Paper Generator
Generate Set A/B/C/D exam papers from 7.5L+ questions in 2 minutes. 3 chapters free.
Try FreeFor Institutes
Online Exam Module
Live online exams with unlimited students, 360° analytics & white-label branding.
See Demo