Telescope — Prelims Questions

An astronomical telescope in normal adjustment has a magnifying power of 25. If the focal length of the eyepiece is $4,\text{cm}$, what is the focal length of the objective lens?

Which of the following optical defects is inherently absent in reflecting telescopes but present in refracting telescopes?

The length of an astronomical telescope in normal adjustment is $120,\text{cm}$. If its magnifying power is 29, what are the focal lengths of the objective and eyepiece?

A reflecting telescope uses a primary mirror of focal length $1.5,\text{m}$. If an eyepiece of focal length $5,\text{cm}$ is used, what is the magnifying power of the telescope?

Which of the following statements about the resolving power of a telescope is correct?

An astronomical telescope is adjusted to form the final image at the least distance of distinct vision ($D = 25,\text{cm}$). If $f_o = 100,\text{cm}$ and $f_e = 5,\text{cm}$, what is the magnifying power?