Which telescope type has plus powered ocular and objective lens?

Which telescope type has plus powered ocular and objective lens?

• A. Keplerian
• B. Galilean
• C. Reflecting
• D. Refracting

Answer: (A)

In this design, both lenses are converging (positive power), which is the defining setup of a Keplerian telescope. A Keplerian telescope uses two convex lenses: a convex objective and a convex eyepiece. This arrangement produces a magnified, inverted image because both lenses bend light toward the optical axis. The other options don’t fit this criterion: a Galilean telescope uses a positive objective but a negative (diverging) eyepiece, so the ocular isn’t plus-powered; a reflecting telescope relies on mirrors rather than two lenses with positive power in the ocular and objective; and a refracting telescope is a general lens-based design, but the specific plus-plus configuration described here is characteristic of the Keplerian arrangement.

In this design, both lenses are converging (positive power), which is the defining setup of a Keplerian telescope. A Keplerian telescope uses two convex lenses: a convex objective and a convex eyepiece. This arrangement produces a magnified, inverted image because both lenses bend light toward the optical axis.

The other options don’t fit this criterion: a Galilean telescope uses a positive objective but a negative (diverging) eyepiece, so the ocular isn’t plus-powered; a reflecting telescope relies on mirrors rather than two lenses with positive power in the ocular and objective; and a refracting telescope is a general lens-based design, but the specific plus-plus configuration described here is characteristic of the Keplerian arrangement.