Geometrical OpticsHard
Question
The figure shows initial positions of a source of light S and a light detector D. Both S & D move with velocity 10 cm/s, as shown. The converging lens of focal length 20 cm is fixed. Time instant(s) when the detector detects maximum intensity of light is /are
Options
A.3 sec
B.4.5 sec
C.6 sec
D.equal intensity at all time
Solution
Detector will detect maximum light when the image of source is formed at the detector.
Let this happens after a time t. At this time u = - (90 - 10t) ; v = 10 t
from lens formula
This gives t = 3 sec & t = 6 sec.
Let this happens after a time t. At this time u = - (90 - 10t) ; v = 10 t
from lens formula
This gives t = 3 sec & t = 6 sec.Create a free account to view solution
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