A screen is place 90 cm from an object the image of object on screen is formed by a convex lens at two different location separated by 20 cm determines focal length of lens.
Answers
Answered by
23
HEY THERE!!
ur answer....
Distance between the image (screen) and the object, D = 90 cm
Distance between two locations of the convex lens, d = 20 cm
Focal length of the lens = f
Focal length is related to d and D as:
f = D²-d²/4D
=(90²)-(20)²/ 4x90
= 770/36
= 21.39cm
Therefore, the focal length of the convex lens is 21.39 cm.
HOPE IT'S HELPFUL FOR YOU....
ur answer....
Distance between the image (screen) and the object, D = 90 cm
Distance between two locations of the convex lens, d = 20 cm
Focal length of the lens = f
Focal length is related to d and D as:
f = D²-d²/4D
=(90²)-(20)²/ 4x90
= 770/36
= 21.39cm
Therefore, the focal length of the convex lens is 21.39 cm.
HOPE IT'S HELPFUL FOR YOU....
Answered by
2
Explanation:
Answer:
f=21.4cm
Explanation:
The image of the object can be located on the screen for two-position of convex lens such that u and v are exchanged.
The separation between two positions of the lens is, d= 20 cm
From the figure,
u1+v1=90cm
v1−u1=20cm
Solving,
v1=55cm,
u1=35cm
From lens formula,
1/v − 1/u = 1/f
1/55 - 1/(-35) = 1/f
1/f = (1/55) + (1/35)
1/f = (55×35)/90
⇒f=21.4cm
Hope it helped.................
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