State what diffraction of a wave means.
Fig. 4.1 shows a setup used to demonstrate light interference. The laser light has wavelength $580\,\text{nm}$, the slit separation is $0.41\,\text{mm}$, and the perpendicular distance from the double slit to the screen is $D$. Coherent light leaves the slits and an interference pattern appears on the screen. The central bright fringe is at point X. The nearest dark fringes to X are at points Y and Z. The distance $XY$ is $2.0\,\text{mm}$. Explain why a bright fringe appears at point X.
State the difference, in $\text{nm}$, between the distances from each slit to point Y.
Fig. 4.1 shows a setup used to demonstrate light interference. The laser light has wavelength $580\,\text{nm}$, the slit separation is $0.41\,\text{mm}$, and the perpendicular distance from the double slit to the screen is $D$. Coherent light leaves the slits and an interference pattern appears on the screen. The central bright fringe is at point X. The nearest dark fringes to X are at points Y and Z. The distance $XY$ is $2.0\,\text{mm}$.
Calculate $D$.
At first, the light intensity passing through the two slits was the same. The intensity through one slit is now reduced. Compare how the fringes look before and after this change in intensity.