In a Fraunhofer diffraction at a single slit,if yellow light illuminating the slit is replaced by blue light,then the diffraction bands

"The person standing behind the open door inside the room can hear the voice of the person standing on the other side of the door but they cannot see each other". Give an experiment based on the diffraction for this statement.

$A$ slit of width $a$ is illuminated by light of wavelength $\lambda$. The linear separation between $1^{st}$ and $3^{rd}$ minima in the diffraction pattern produced on a screen placed at a distance $D$ from the slit system is . . . . . . .

The phenomenon of diffraction occurs in .......

$A$ slit of width $d$ is illuminated by white light. The first minimum for red light $(\lambda = 6500\,\mathring{A})$ will fall at $\theta = 30^\circ$ when $d$ will be

$A$ single slit of width $a$ 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