A ray of light is incident at an angle $i$ on one face of a thin angled prism. The ray emerges normally from the other face. Refractive inder of the glass prims is $n$ and angle of prism is $A$. The value of $i$ is

An object is clearly seen through an astronomical telescope of length 50 cm . The focal lengths of its objective and eye-piece respectively, can be

By increasing the aperture of the objective lens, wavelength of light, focal length of the objective lens and the resolving power of an astronomical telescope respectively

There are four convex lenses $$L_1, L_2, L_3$$ and $$L_4$$ of focal length $$2,4,6$$ and 8 cm, respectively. Two of these lenses from a telescope of length 10 cm and magnifying power 4. The objective and eye lenses are respectively