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

Consider diffraction of light through a rectangular slit which is twice as wide as it is high. Which of the following statements is true?

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.....$^{\circ}$

Which of the following waves exhibits clear diffraction?

$A$ parallel beam of light of wavelength $500\; nm$ falls on a narrow slit and the resulting diffraction pattern is observed on a screen $1\;m$ away. It is observed that the first minimum is at a distance of $2.5\;mm$ from the centre of the screen. Find the width of the slit. (in $; mm$)

$A$ slit of width $d$ is illuminated by light of wavelength $\lambda$. The angular width of the central maximum is: