In Fresnel diffraction, if the distance between the disc and the screen is decreased, the intensity of central bright spot will

Question

In Fresnel diffraction, if the distance between the disc and the screen is decreased, the intensity of central bright spot will (A) Increase (B) Decrease (C) Remain constant (D) None of these

Tardigrade Admin · Accepted Answer

A=n π d λ ⇒ n d=(A/π λ)= constant ⇒ n propto (1/d)( n = number of blocked H P Z) on decreasing d, n increases, hence intensity decreases.

Q. In Fresnel diffraction, if the distance between the disc and the screen is decreased, the intensity of central bright spot will

Increase

Decrease

Remain constant

None of these

$A = nπ d λ \Rightarrow n d = \frac{A}{πλ} =$ constant
$\Rightarrow n \propto \frac{1}{d} (n =$ number of blocked $H PZ)$ on decreasing $d$ ,
$n$ increases, hence intensity decreases.

Q. In Fresnel diffraction, if the distance between the disc and the screen is decreased, the intensity of central bright spot will

Increase

Decrease

Remain constant

None of these

A=nπdλ⇒nd=πλA​= constant ⇒n∝d1​(n= number of blocked HPZ) on decreasing d, n increases, hence intensity decreases.

$A = nπ d λ \Rightarrow n d = \frac{A}{πλ} =$ constant
$\Rightarrow n \propto \frac{1}{d} (n =$ number of blocked $H PZ)$ on decreasing $d$ ,
$n$ increases, hence intensity decreases.