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

Write the thoughts expressed by Richard Feynman regarding the difference between interference and diffraction.

$A$ 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 $.....$

$A$ slit of size '$a$' is illuminated by a parallel beam of light of wavelength $\lambda$. The angle at which this light is diffracted is approximately . . . . . . .

The bending of a beam of light around the corners of obstacles is called

$A$ parallel beam of light of wavelength $6000 \text{ Å}$ is diffracted by a single slit of width $0.3 \text{ mm}$. The angular position of the first minima of the diffracted light is