Ray Optics And Optical Instruments
when two thin lenses are in contact than 1/F = 1/f1 + 1/f2
power of lense = 1/focal lenth
so, +7D+ -3D = +4D
focal length of comb.=+4D
The critical angle for a pair of media is 60 digree.the refractive index of the denser medioum relative to the rarer mesium is
P=7+(-3) =+4D F=1/D=100/4 =25cm
Text Solution
Solution : Here `P_(1) = 5D, P_(2) = - 3D` <br> Power of combination of lenses, <br> `P = P_(1) + P_(2) = 5D - 3D = 2D` <br> `:.` Focal length of combination, <br> `f=(1)/(p)=(1)/(2) m = 50 cm`.
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