Consider the path of a ray of light passing through a rectangular glass slab for different angles of incidence. (i) Which one is greater: angle of incidence or angle of refraction? (ii) What happens to the emergent angle on increasing the incident angle at air-glass interface? (iii) State the conditions when no refraction occurs. 2
OR
Sunita takes a mirror which is depressed at the centre and mounts it on a mirror stand. An erect and enlarged image of her face is formed. She places the mirror on a stand along a meter scale at 15 cm mark. In front of this mirror, she mounts a white screen and moves it back and forth along the meter scale till a sharp, well-defined inverted image of a distant tree is formed on the screen at 35 cm mark.
(i) Name the mirror and find its focal length.
(ii) Why does Sunita get sharp image of the distant building at 35 cm mark?
Answers
So the critical angle is defined as the angle of incidence that provides an angle of refraction of 90-degrees. Make particular note that the critical angle is an angle of incidence value.
OR
Q. Sunita takes a mirror which is depressed at the centre and mounts it on a mirror stand. An erect and enlarged image of her face is formed. She places the mirror on a stand along a meter scale at 15 cm mark. In front of this mirror, she mounts a white screen and moves it back and forth along the meter scale till a sharp, well-defined inverted image of a distant tree is formed on the screen at 35 cm mark.
(i) Name the mirror and find its focal length.
(ii) Why does Sunita get sharp image of the distant building at 35 cm mark?
Ans.
(i) The mirror used by Sunita is a convex mirror. Since it gives a clear image of a distant object at 35cm, the focal length of the mirror is also 35cm.
(ii)Since the focal length has been determined to be 35cm, we know that incoming light rays from infinity will converge at the focus. Since the tree is distant, we can approximate it to be located at infinity. As a result, Sunita gets a clear image of a distant object at the focus of her mirror (white screen).
The question is already answered by Prmkulk1978 :
brainly.in/question/6769429
Hope this helps!
i) The mirror used by Sunita is Concave mirror as she gets her image of face as erect and enlarged.
Only concave mirrors can produce virtual and erect image when object is placed in between Pole and Focus.
ii) As a distant object which is regarded as placed At infinity, image is formed well defined and sharp at 35cm.
hence focal length of the mirror is 35cm.[ Because concave mirror will form image at focus when object is placed at infinity.]