Geometrical OpticsHard
Question
The intensity of light from a source decreases with the distance x from the source, as 
picture, the intensity of light from the source S at point A on a curtain is 8.1 U, where U is some unit. Then we add a big mirror parallel to the curtain at point B. The distances AS and SB are equal, and the points A, S and B are in line, perpendicular to the curtain and the mirror. What is the intensity in U of light reaching point A now ?
picture, the intensity of light from the source S at point A on a curtain is 8.1 U, where U is some unit. Then we add a big mirror parallel to the curtain at point B. The distances AS and SB are equal, and the points A, S and B are in line, perpendicular to the curtain and the mirror. What is the intensity in U of light reaching point A now ?Options
A.9
B.15
C.12
D.18
Solution
Inet = IA + IB
IB =
, IA = 
= 8.1μInet = 8.1μ +
Inet = 9μ
Create a free account to view solution
View Solution FreeMore Geometrical Optics Questions
The focal length of a convex mirror is 20 cm its radius of curvature will be...An astronomical telescope of magnifying power 8 is made using two lenses spaced 45 cm apart. The focal length of the len...Two thin lenses, one of focal length + 60 cm and the other of focal length -20 cm are put in contact. The combined focal...Two plane mirrors are lying perpendicular to each other, there is lamp in between mirrors. Then No. of images of lamp wi...A ray of light incident on a concave mirror. It is parallel to the principal axis and its height from principal axis is ...