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Assertion:- Newton's rings are formed in...

Assertion:- Newton's rings are formed in the reflected system. When the space between the lens and the glass place is filled with a liquid of regractive index greater than that of glass, the central spot of the pattern is bright.
Reason:- This is because the reflection in these cases will be from a denser to raer medium and the two interfering rays are reflected under similar conditions.

A

Both A and R are true and R is the correct explanation of A

B

Both A and R are true and R is not the correct explanation of A

C

A is true and R is false

D

Both A and R are false

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The correct Answer is:
A
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Assertion : Newton's rings are formed in the reflected system. When the space between the lens and the glass plate is filled with a liquid of refractive index greater than that of glass, the central spot of the pattern is bright. Reason : This is because the reflections in these cases will be from a denser to a rarer medium and the two interfering rays are reflected under similar conditions.

A thin bi-convex lens made up of glass of refractive index 3//2 is placed is front of a plane mirror. The space between the lens and the mirror is filled with water of refractive index 4//3 . The radii of curvatures of the lens are R_(1)=15cm and R_(2)=25 cm . A point object is placed at distance x from the surface whose curvature is R_(1) . The distance x is greater than the separation between the lens and the mirror. Find the value of x so that image must coincide with the object.

Assertion: White light is incident on face AB of an isosceles right angled prism as shown. Colours, for which refractive index of material of prism is more than 1.414, will be able to emerge from the face AC. Reason:Total internal reflection cannot take place for the light travelling from a rarer medium to a denser medium.

A ray of light travelling with a speed c leaves point 1 shown in figure and is reflected to point 2. The ray strikes the reflecting surface at a distance x from point 1. According to Fermat's principle of least time, among all possible paths between two points , the one actually taken by a ray of light is that for which the time taken is the least (In fact there are some cases in which the time taken by a ray is maximum rather than a minimum). Under what condition is time taken least?

Thin films, including soap bubbles and oil show patterns of alternative dark and bright regions resulting from interference among the reflected ligth waves. If two waves are in phase, their crests and troughs will coincide. The interference will be cosntructive and the amlitude of resultant wave will be greater then either of constituent waves. If the two wave are not of phase by half a wavelength (180^(@)) , the crests of one wave will coincide width the troughs of the other wave. The interference will be destructive and the ampliutde of the resultant wave will be less than that of either consituent wave. 1. When incident light I, reaches the surface at point a, some of the ligth is reflected as ray R_(a) and some is refracted following the path ab to the back of the film. 2. At point b, some of the light is refracted out of the film and part is reflected back through the film along path bc. At point c, some of the light is reflected back into the film and part is reflected out of the film as ray R_(c) . R_(a) and R_(c) are parallel. However, R_(c) has travelled the extra distance within the film fo abc. If the angle of incidence is small, then abc is approxmately twice the film's thickness . If R_(a) and R_(c) are in phase, they will undergo constructive interference and the region ac will be bright. If R_(a) and R_(c) are out of phase, they will undergo destructive interference and the region ac will be dark. I. Refraction at an interface never changes the phase of the wave. II. For reflection at the interfere between two media 1 and 2, if n_(1) gt n_(2) , the reflected wave will change phase. If n_(1) lt n_(2) , the reflected wave will not undergo a phase change. For reference, n_(air) = 1.00 . III. If the waves are in phase after reflection at all intensities, then the effects of path length in the film are: Constrictive interference occurs when 2 t = m lambda // n, m = 0, 1,2,3 ,... Destrcutive interference occurs when 2 t = (m + (1)/(2)) (lambda)/(n) , m = 0, 1, 2, 3 ,... If the waves are 180^(@) out of the phase after reflection at all interference, then the effects of path length in the film ara: Constructive interference occurs when 2 t = (m + (1)/(2)) (lambda)/(n), m = 0, 1, 2, 3 ,... Destructive interference occurs when 2 t = (m lambda)/(n) , m = 0, 1, 2, 3 ,... The average human eye sees colors with wavelength between 430 nm to 680 nm. For what visible wavelength (s) will a 350 nm thick (n = 1.35) soap film produce maximum destructive interference?

A glass wedge with a small angle of refraction theta is placed at a certain distance from a converging lens with a focal length f ,one surface of the wedge being perpendicular to the optical axis of the lens. A point sources S of light is on the other side of the lens at its focus. The rays reflected from the wedge (not from base) produce, after refraction in the lens , two images of the source displaced with respect to each other by d. Find the refractive index of the wedge glass. [Consider only paraxial rays.]

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 . Consider an air wedge formed by two glass plates. having refractive index 1.5 by placing a piece of paper of thickness 20 mm. Determine the number of dark bands formed.

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") = 400 nm ,h=20mm. In question 53, if air wedge has been filled with a medium having refractive index 1.3 then find the number of bright bands.

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

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 data in question53 determine the distance of point B from the 20th dark band. Counting of dark point has to start from the contact point.

AAKASH SERIES-WAVES OPTICS-EXERCISE -IB (ASSERTION AND REASON)
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