Advertisements
Advertisements
Question
Why do the faces of persons sitting around campfire appear to shimmer?
Solution
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.
APPEARS IN
RELATED QUESTIONS
Light of a single colour is passed through a liquid having a piece of glass suspended in it. On changing the temperature of liquid, at a particular temperature the glass piece is not seen. When is the glass piece not seen?
How does the angle of deviation produced by a prism change with increase in the angle of incidence. Draw a curve showing the variation in the angle of deviation with the angle of incidence at a prism surface.
Complete Fig. 4.32 to show the path of the ray of single colour as it enters the prism and emerges out of it. Mark the angles wherever necessary.
A total reflecting right angled isosceles prism can be used to deviate a ray of light through:
(a) 30° (b) 60° (c) 75° (d) 90°.
Four students showed the following traces of the path of a ray of light passing through a rectangular glass slab.
The trace most likely to be correct is that of student
(A) I
(B) II
(C) III
(D) IV
Fig shows a lens as a combination of a glass block and two prisms.
(i) Name the lens formed by the combination.
(ii) what is the XX' called?
(iii) Complete the ray diagram and show the path of the incident ray PQ after passing through the lens.
(iv) The final emergent ray will either meet XX' at a point or appear to come from a point on XX'. what is the point called?
Which colour of light travels fastest in any medium except air?
Does the depth of a tank of water appear to change or remain the same when viewed normally from above?
The diagram shows the path of a ray of light through a rectangular glass block placed in a liquid of uniform density.
What is the angular, deviation of the emergent ray from the glass block with respect to the incident ray?
The speed of light in air is 3 × 108 ms-1. Calculate the speed of light in water. The refractive index of water is 4/3.
