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A glass of refractive index 1.5 is coate...

A glass of refractive index 1.5 is coated with a thin layer of thickness t and refractive index 1.8 . Light of wavelength `lambda` travelling in air is incident normally on the layer. It is partly reflected at the upper and the lower surfaces of the layer. It is partly reflected at the upper and the lower surfaces of the layer ant the two reflected rays interface . If `lambda = 648 nm`, obtain the least value of `t ("in" 10^(-8)m )` which the rays interface constructively.

Answer

Step by step text solution for A glass of refractive index 1.5 is coated with a thin layer of thickness t and refractive index 1.8 . Light of wavelength lambda travelling in air is incident normally on the layer. It is partly reflected at the upper and the lower surfaces of the layer. It is partly reflected at the upper and the lower surfaces of the layer ant the two reflected rays interface . If lambda = 648 nm, obtain the least value of t ("in" 10^(-8)m ) which the rays interface constructively. by PHYSICS experts to help you in doubts & scoring excellent marks in Class 12 exams.

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(a) A convex lens of focal length 15cm and a concave mirror of focal length 30 cm are kept with their optic axes PQ and RS parallel but separated in vertical direction by 0.6 cm as shown. The distance between the lens and mirror is 30 cm. An upright object AB of height 1.2 cm is placed on the optic axis PQ of the lens at a distance of 20 cm from the lens. If A^ B^ is the image after refraction from the lens and reflection from the mirror, find the distance of A^ B^ from the pole of the mirror and obtain its magnification. Also locate position of A^ and B^ with respect to the optic axis RS. (b) A glass plate of refractive index 1.5 is coated with a thin layer of thickness t and refractive index 1.8. Light of wavelength lamda travelling in air is incident normally on the layer. It is partly reflected at the upper and the lower surface of the layer and the two reflected rays interfere. Write the condition for their constructive interference. if lamda=648nm , obtain the least value of t for which the rays interfere constructively.

The outer surface of a transparent glass slab of refractive index mu_(S)=1.5 is coated by a thin layer of transparent medium of refractive index mu_(C)=1.6 . Orange light of wavelength 6400Å falls normally on the coating. The reflected light at the upper surface and at the lower surface of teh coat interfere destructively. If thickness of the coat is 5Kxx10^(-8) m, calculate the minimum value of K.

Knowledge Check

  • A wave travelling in air falls on a glass plate . It is partly reflected and partly refracted. What is the phase difference between the reflected and refracted waves ?

    A
    `2pi`
    B
    `pi`
    C
    `(pi)/2`
    D
    zero

  • White light is incident normally on a glass plate (in air) of thickness 500 nm and refractive index of 1.5. The wavelength (in nm) in the visible region (400 nm - 700 nm) that is strongly reflected by the plate is :

    A
    450
    B
    600
    C
    400
    D
    500

  • White light is incident normally on a glass plate (in air) of thickness 500 nm and refractive index of 1.5 . The wavelength (in nm ) in the visible region (400 nm-700nm) that is strongly reflected by the plate is:

    A
    `450`
    B
    `600`
    C
    `400`
    D
    `500`

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