$A$ single slit of width $d$ is illuminated by violet light of wavelength $400 \ nm$ and the width of the diffraction pattern is measured as $Y$. When half of the slit width is covered and illuminated by yellow light of wavelength $600 \ nm$,the width of the diffraction pattern is

$A$ single slit diffraction experiment is performed to determine the slit width using the equation,$\frac{b d}{D} = m \lambda$,where $b$ is the slit width,$D$ is the distance between the slit and the screen,$d$ is the distance between the $m^{\text{th}}$ diffraction maximum and the central maximum,and $\lambda$ is the wavelength. $D$ and $d$ are measured with scales of least count of $1 \ cm$ and $1 \ mm$,respectively. The values of $\lambda$ and $m$ are known precisely to be $600 \ nm$ and $3$,respectively. The absolute error (in $\mu m$) in the value of $b$ estimated using the diffraction maximum that occurs for $m=3$ with $d=5 \ mm$ and $D=1 \ m$ is $.....$

In a single slit diffraction experiment,when the distance of separation between the slit and the screen is doubled,the angular separation between the fringes

Light of wavelength $5000 \, \mathring{A}$ is incident on a single slit such that the angular position of the first minima is $30^\circ$. The width of the slit is:

When a compact disc $(CD)$ is illuminated by a small source of white light,coloured bands are observed. This is due to

Assertion : When a tiny circular obstacle is placed in the path of light from some distance,a bright spot is seen at the centre of the shadow of the obstacle.
Reason : Destructive interference occurs at the centre of the shadow.