NCERT 2022 | प्रकाश परावर्तन तथा अपवर्तन - L7 | light reflection and refraction | Ruchi Ma'am| 6 PM

In the figure shown S is a point monochromatic light source of frequency 6xx10^(14)Hz .M is a concave mirror of radius of curvature 20 cm and L is a thin converging lens of focal length 3.75 cm AB is the principal axis of M and L. Light reflected from the mirror and refracted from the lens in succession reaches the screen. An interference pattern is obtained on the screen by this arrangement. Q. Distance between two coherent sources whichmakes interference pattern on the screen is

In the figure shown S is a point monochromatic light source of frequency 6xx10^(14)Hz .M is a concave mirror of radius of curvature 20 cm and L is a thin converging lens of focal length 3.75 cm AB is the principal axis of M and L. Light reflected from the mirror and refracted from the lens in succession reaches the screen. An interference pattern is obtained on the screen by this arrangement. Q. Fringe width is

In the figure shown S is a point monochromatic light source of frequency 6xx10^(14)Hz .M is a concave mirror of radius of curvature 20 cm and L is a thin converging lens of focal length 3.75 cm AB is the principal axis of M and L. Light reflected from the mirror and refracted from the lens in succession reaches the screen. An interference pattern is obtained on the screen by this arrangement. Q. If the lens is replaced by another converging lens of focal length (10)/(3)cm and the lens is shifted towards right by 2.5 cm then

This interference film is used to measure the thickness of slides, paper, etc. The arrangement is as shown in fig. For the sake of clarity, the two strips are shown thick. Consider the wedge formed in between strips 1 and 2. If the interference pattern because of the two waves reflected from wedge surface is observed, then from the observed data we can compute thickness of paper, refractive index of the medium filled in wedge, number of bonds formed, etc. Considre the strips to be thick as compared to wavelength of ligth and light is incident normally. Neglect the effect due to reflection from top surface of strip 1 and bottom surface of strip 2. Take L = 5 cm and lambda_(air) = 40 nm . For strip 1 refractive index is 1.34 abd for strip 2 refractive index is 1.6 The wedge. is filled with a medium having refractive index 1.5. Then

A thin oil film of refracting index 1.2 floats on the surface of water (mu=4/3) . When a light of wavelength lamda=9.6xx10^(-7)m falls normally on the film air, then it appears dark when seen normally. The minimum change in its thickness for which it will appear bright in normally reflected light by the same light is Zxx10^(-7)m . Then find Z .