Two lenses shown in figure. Are illuminated by a beam of parallel light from the left. Lens B is then moved slowly toward lens A. the beam emerging from lens B is

A thin convex lens (L_(1)) of focal length 80 cm and a thin concave lens (L_(2)) of focal length f are kept co-axially, 20 cm apart as shown in figure below. When a narrow and parallel beam of light is incident on the conver lens, beam emerging from the concave lens is also a parallel beam. Find f.

Two thin lenses are placed 5cm apart along the same axis and illuminted with a beam of light parallel to that axis. The first lens in the path of the beam is a converging lens of focal length 10cm whereas the second is a diverging lens of focal length 5cm. If the second lens if now moved toward the first, the emergent light

Two thin lenses are placed 5cm apart along the same axis and illuminted with a beam of light parallel to that axis. The first lens in the path of the beam is a converging lens of focal length 10cm whereas the second is a diverging lens of focal length 5cm. If the second lens if now moved toward the first, the emergent light

A parallel beam of light after refraction through a lens, converges toward its principal focus. What kind of lens is it?

A convex lens of focal length 1.0m and a concave lens of focal length9.25m are 0.75m apart. A parallel beam of light is incident on the convex lens. The beam emerging after refraction from both lenses is

A convex lens of focal length 1.0m and a concave lens of focal length 0.25m are 0.75m apart. A parallel beam of light is incident on the convex lens. The beam emerging after refraction from both lenses is

Which of the two diverges a beam of parallel rays of light : convex lens or concave lens ?

A convex lens of focal length 20cm and a concave lens of focal length f are mounted coaxially 5cm apart. Parallel beam of light incident on the convex lens emerges from the concave lens as a parallel beam. Then, f in cm is