Four convergent lenses have focal lengths $100cm,10cm,4cm$ and $0.3cm$, for a telescope with maximum possible magnifications we choose the lenses of following focal lengths :

Q. Four lenses of focal length $\pm 15$ cm and $\pm 150$cm are available for making a telescope. To produce the largest magnification, the focal length of the eyepiece should be

Q. Four lenses of focal length 15 cm, 20 cm, 150 cm and 250 cm are available for making an astronomical telescope. To produce the largest magnification, what should the focal length of the eyepiece be?

Q. Four lenses having the focal length of + 15 cm, 20cm, + 150cm, and +250cm respectively are provided to make an astronomical telescope. The focal length of the eyepiece to produce the. largest magnification, should be.

Q. A converging lens of focal length 30 cm is placed in contact with another converging lens of unknown focal length, then possible value for focal length of combination is