If the path difference of the point on the screen from a coherent source is constant, what is shape of trajectory of the point on the screen ?

What are coherent sources ?

For light diverging from a point source

In Young's double-slit experiment using monochromatic light of wavelength lambda , the intensity of light at a point on the screen where path difference is lambda , is K units. What is the intensity of light at a point where path difference is lambda//3 ?

Discuss the pattern of interference fringes obtained on the screen away from the two point sources.

In Young's double-slit experment, the frist maxima is observed at a fixed point P on the screen. Now, the screen is continously moved away from the plane of slits. The ratio of intensity at point P to the intensity at point O (center of the screen)

The path difference between two interfering waves at a point on the screen is lambda // 6 , The ratio of intensity at this point and that at the central bright fringe will be (assume that intensity due to each slit is same)

A thin glass plate of thickness t and refractive index mu is inserted between screen and one of the slits in a young's experiment. If the intensity at the centre of the screen is I, what was the intensity at the same point prior to the introduction of the sheet.

Obtain the formula of path difference at a point on the screen in Young's double slit experiment in term of x, d and D.