Superposition & Coherent sources - Lec 12 - Optics

What are coherent sources ?

A pair of coherent sources may be

In young's double slit experiment if the seperation between coherent sources is halved and the distance of the screen from coherent sources is doubled, then the fringe width becomes:

Two coherent sources must have the same

If the ratio of the intensity of two coherent sources is 4 then the visibility [(I_(max)-I_(min))//(I_(max)+I_(min))] of the fringes is

In Young’s experiment, the ratio of maximum to minimum intensities of the fringe system is 4 : 1 . The amplitudes of the coherent sources are in the ratio

The intensity ratio of two coherent sources of light is p. They are interfering in some region and produce interference patten. Then the fringe visibility is

In Fresnel bi-prism experiment a coherent source and screen are placed at a distance very greater than size of prism. Angle theta is very small, if the source is shifted slightly vertically upward then

Two small angled transparent prisms (each or refracting angle A = 1^(@)) are so placed that their bases coincide, so that common base is BC. This device is called Fresnel's biprism and is used to obtain coherent sources of a point source S illuminated by monochromatic light of wavelength 6000 Å placed at a distance a = 20 cm. Calculate the separation between coherent sources. If a screen is placed at a distance b = 80 cm. from the device, what ist the finge which of fringes obtained (Refractive index of material of each prism = 1.5.)

Consider the following statement A and B and identify the correct answer A) In the case of narrow source of light coherent sources are obtained by the division of wave front B) Diffraction is due to interference of light from secondary sources of the same wave front whereas interference is due to superposition of two waves derived from the same source.