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प्रश्न
How will you verify the laws of refraction or how the refractive index of glass is determined in the laboratory?
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उत्तर
Place a white sheet of paper on a drawing board. Put a rectangular slab of glass on this white sheet and trace out its boundary ABCD. At any point R on the edge AB, draw a normal NN’. Draw an incident ray PR at any angle say 30°. Fix two pins P1 and P2 vertically on the line PR and at a distance not less than 3 cm from each other. Looking through the other side of the block, fix two pins, P3 and P4 vertically on the white sheet, such that all the four pins P1, P2, P3, and P4 appear to be in a straight line as seen through the glass block. Mark the pinpoints with a fine pencil, remove the block and join the points P3 and P4 by the straight line RS.
PR represents the incident ray and RS represents the refracted ray. ∠PRN and ∠KRN’ are respectively angles of incidence and refraction.
With R as centre and convenient radius, draw a circle cutting the incident ray at Q and the refracted ray at Q’.
From Q and Q’, draw perpendiculars QT and QT’ on the normal NN’
Now sin i = `"QT"/"QR"`
and Sin r = `"Q’T’"/"Q’T’"`
μ = `Sin"i"/Sin"r"="QT"/"QR"."Q’R"/"Q’T’"="QT"/"Q’T’"`
Since QR = Q’R being the radius of the same circle.
Repeat this experiment for other angles of incidence, say 45° and 60°, and find μ.
It is found that for different values of i the ratio.
`sin"i"/Sin"r"` = constant
Thus, it is verified that,
(i) `sin"i"/Sin"r"` is a constant and is equal to aμg.
(ii) The incident the refracted ray and normal line in the same plane.
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संबंधित प्रश्न
When a ray of light travels from air to glass slab and strikes the surface of separation at 90°, then it …………….
(a) bends towards normal
(b) bends away from normal
(c) passes unbent
(d) passes in zigzag way
A student very cautiously traces the path of a ray through a glass slab for different values of the angle of incidence (∠i). He then measures the corresponding values of the angle of refraction (∠r) and the angle of emergence (∠e) for every value of the angle of incidence. On analysing these measurements of angles, his conclusion would be
(A) ∠i > ∠r > ∠e
(B) ∠i = ∠e > ∠r
(C) ∠i < ∠r < ∠e
(D) ∠i = ∠e < ∠r
Name one factor that affects the lateral displacement of light as it passes through a rectangular glass slab.
A postage stamp kept below a rectangular glass block of refractive index 1.5 when viewed from vertically above it, appears to be raised by 7.0 mm. Calculate the thickness of the glass slab.
What is the refractive index of water
How does the angle of deviation produced by a prism depend on the colour of light used? Which colour of white light is deviated (i) most, (ii) least, by a prism?
The refractive index of air with respect to glass is defined: as gµa = sin i/sin r
If r = 90°, what is the corresponding angle i called?
Draw ray of light bending towards the normal while passing from air to glass. Label your diagrams.
The figure shows two prisms A and B. A monochromatic ray of light PO is incident at the face of the prism A. Complete the diagram to show the path of the ray till it emerges out of the prism B.
Write the approximate values of speed of light in (i) air and (ii) glass. Use these values to calculate the refractive index of glass with respect to air.
