Obtain the formulas for the angular width and linear width of the central maximum in a single-slit diffraction experiment.

Vedclass pdf generator app on play store
Vedclass iOS app on app store
(N/A) The width of the central maximum is defined as the distance between the first minima on either side of the central maximum.
Let the width of the slit be $a$ and the distance between the slit and the screen be $D$.
For the first minimum on one side of the central maximum,the condition for diffraction is given by $a \sin \theta = \lambda$. Since $\theta$ is very small,$\sin \theta \approx \theta$,so $\theta = \frac{\lambda}{a}$.
Here,$\theta$ represents half the angular width of the central maximum.
Therefore,the total angular width of the central maximum is $2\theta = \frac{2\lambda}{a}$.
Now,for the linear width $\beta_0$,we use the relation between arc length,radius,and angle: $\text{arc} = \text{radius} \times \text{angle}$.
Here,the arc length is $\beta_0$,the radius is $D$,and the angle is $2\theta$.
Thus,$\beta_0 = D \times (2\theta) = D \times \frac{2\lambda}{a}$.
Therefore,the linear width of the central maximum is $\beta_0 = \frac{2D\lambda}{a}$.

Explore More

Similar Questions

$A$ parallel monochromatic beam of light is incident normally on a narrow slit. $A$ diffraction pattern is formed on a screen placed perpendicular to the direction of the incident beam. At the first maximum of the diffraction pattern,the phase difference between the rays coming from the edges of the slit is

$A$ parallel beam of light of wavelength $\lambda$ is incident normally on a single slit of width $d$. Diffraction bands are obtained on a screen placed at a distance $D$ from the slit. The second dark band from the central bright band will be at a distance given by

$A$ slit of width $12 \times 10^{-5} \ cm$ is illuminated by monochromatic light of wavelength $6000 \ \mathring A$. Find the half angular width of the central bright maximum in the Fraunhofer diffraction pattern in degrees $(^o)$.

Visible light of wavelength $6000 \times 10^{-8} \; cm$ falls normally on a single slit and produces a diffraction pattern. It is found that the second diffraction minimum is at $60^{\circ}$ from the central maximum. If the first minimum is produced at $\theta_{1}$,then $\theta_{1}$ is close to.....$^{\circ}$

The waves of $600 \ \mu m$ wavelength are incident normally on a slit of $1.2 \ mm$ width. The value of diffraction angle corresponding to the first minima will be (in radian) -

Vedclass Products

For Students

Vedclass Test Series

Mock tests in real JEE/NEET style with performance analysis. 5-day free trial.

Start Free Trial
For Teachers

Exam Paper Generator

Generate Set A/B/C/D exam papers from 7.5L+ questions in 2 minutes. 3 chapters free.

Try Free
For Institutes

Online Exam Module

Live online exams with unlimited students, 360° analytics & white-label branding.

See Demo