(a) Define focal length of a divergent lens.
(b) A divergent lens of focal length 30 cm forms the image of an object of size 6 cm on the same side as the object at a distance of 15 cm from its optical centre. Use lens formula to determine the distance of the object from the lens and the size of the image formed.
(c) Draw a ray diagram to show the formation of image in the above situation.

Dear Student,
Please find below the solution to the asked query:

a) The point from which light rays parallel to the principle axis appear to diverge from is called principle focus of a diverging lens. The distance between principle focus and optic centre is known as the focal length of a divergent lens.

b) Given here:
f = -30 cm
v = -15 cm 
using the lens formula:
1f=1v-1u1-30=1-15-1u1u= 130-1151u=1-30u= -30 cm also, if h' is the height of the mimage formed then,m = vu=h'h-15-30=h'6h' = 3cm
C) ray diagram is as under:



Hope this information will clear your doubts about (Light).
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Regards
Satyendra Singh

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