A parallel beam of light is incident on the system of two convex lenses of focal length `f_(1)=20cm` and `f_(2)=10cm` . What should be the distance between the two lenses so that rays after refraction from both the lenses pass undeviated?

A parallel beam of monochromatic light falls on a combination of a convex lens and a concave lens of focal lengths 15 cm and 5 cm respectively. What is the distance between the two lenses to obtain a parallel beam of light from the concave lens ?

A parallel beam of monochromatic light falls on a combination of a convex lens and a concave lens of focal lengths 15 cm and 5 cm respectively. What is the distance between the two lenses to obtain a parallel beam of light from the concave lens ?

Two convex lenses of focal length 10 cm each are combined. What will be the focal length of the combined lens ?

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

Two convex lenses of focal lengths f_(1) and f_2 are separated co-axially by a distance d. The power of the combination will be one if

Two convex lenses of focal length f_1 and f_2 are mounted coaxially separated by a distance. If the power of the combination is zero, the distance between the lenses is

Two convex lenses of focal length f_1 and f_2 are mounted coaxially separated by a distance. If the power of the combination is zero, the distance between the lenses is