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Question
Why upper surface of water contained in a beaker and above eye level appears silvery?
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Solution
Critical angle for water is 49°. The rays of light entering the water from below, suffer refraction. If these rays strike the water-air surface at an angle which is greater than 48°, they get totally internally reflected. These rays on emerging out of the water, appear to come from the upper surface of the water, which in turn appears silvery.
RELATED QUESTIONS
Study the following four experimental set-ups I, II, III and IV for the experiment, "To trace the path of a ray of light through a rectangular glass slab."
Which of the marked set-ups is likely to give best results (P1 and P2 are the positions of pins fixed on the incident ray)?
(A) I
(B) II
(C) III
(D) IV
How does the angle of minimum deviation produces by a prism change with increase in :
the wavelength of incident light
How is the angle of emergence related to the angle of incidence when prism is in the position of minimum deviation? Illustrate your answer with help of a labelled diagram using an equilateral prism?
The refractive index of air with respect to glass is expressed as `""_g μ_a=sin i /sin r`.
- Write down a similar expression for aμg in terms of the angles i and r.
- If angle r = 90°, what is the corresponding angle i called?
- What is the physical significance of the angle i in part (b)?
Trace the path of a ray of light incident at an angle of 45° on a rectangular glass slab. Write the measure of the angle of refraction, the angle of emergence and the lateral displacement suffered by the ray as it passes through the slab.
Select from the following the best set-up for tracing the path of a ray of light through a rectangular glass slab:
(A) I
(B) II
(C) III
(D) IV
A student traces the path of a ray of white light through a rectangular glass slab and marks, the angles of incidence (∠i) , refraction (∠r) and emergence (∠e) as shown. Which angle or angles has he not marked correctly?
(A) ∠i only
(B) ∠i and ∠r
(C) ∠i and ∠e
(D) ∠r and ∠e
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?
