In Fig., there are two convex lenses `L_1 and L_2` having focal lengths `F_1` and `F_2` respectively. The distance between `L_1` and `L_2` will be :
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In the figure given below there are two convex lenses L1 and L2 having focal lengths F1 and F2 respectively. The distance between L1 and L2 will be

In the figure shown, there are two convex lenses L_(1) and L_(2) having focal. Lengths f_(1) and f_(2) respectively. The distance between L_(1) and L_(2) will be

In the figure shown, there are two convex lenses L_(1) and L_(2) having focal. Lengths f_(1) and f_(2) respectively. The distance between L_(1) and L_(2) will be

Two convex lenses of focal lengths f_1 and f_2 respectively are placed in contact each other. Then what will be power of their equivalent lens?

Deduce the equivalent focal length of two convex lenses of focal lengths F_(1) and F_(2) when placed in contact.

An eyepiece of a telescope consists of two plano-convex lenses L_(1) and L_(2) each of focal length f separated by a distance of 2f/3. where should L_(1) be plaecd relative to the focus of the objective lens of the telescope so that the final image through L_(2) is seen at infinity ?