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प्रश्न
Why do the faces of persons sitting around campfire appear to shimmer?
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उत्तर
The rays coming from the face of the person, sitting across the campfire, suffer refraction on passing through hot air. Thus, we see the apparent image of the person. Since hot air is in motion, therefore its optical density changes, which in turn shifts the image rapidly. This rapidly shifting image gives a shimmering effect.
संबंधित प्रश्न
Define refraction and state the laws of refraction.
After tracing the path of a ray of light passing through a rectangular glass slab for four different values of the angle of incidence, a student reported his observations in tabular form as given below:
| S.No | ∠ i | ∠ r | ∠ e |
| I | 30° | 19° | 29° |
| II | 40° | 28° | 40° |
| III | 50° | 36° | 50° |
| IV | 60° | 40° | 59° |
The best observation is
(A) I
(B) II
(C) III
(D) IV
Name a prism required for obtaining a spectrum of Ultraviolet light.
Light passes through a rectangular glass slab and through a triangular glass prism. In what way does the direction of the two emergent beams differ and why?
How must light travel out of a substance if it is not going to be refracted?
Draw diagrams to show the refraction of light from
- air to glass, and
- glass to air. In each diagram, label the incident ray, refracted ray, the angle of incidence
- and the angle of refraction (r).
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.
The critical angle for glass-air interface is :
What do you understand by the deviation produced by a prism?
