Optical Instruments — Prelims Questions

A simple microscope has a focal length of $5\,\text{cm}$. If the final image is formed at the least distance of distinct vision ($D = 25\,\text{cm}$), what is its magnifying power?

A compound microscope has an objective lens of focal length $1\,\text{cm}$ and an eyepiece of focal length $5\,\text{cm}$. If the final image is formed at infinity and the length of the microscope tube is $20\,\text{cm}$, what is the approximate magnifying power of the microscope? (Assume $D = 25\,\text{cm}$)

An astronomical telescope in normal adjustment has a magnifying power of 20. If the focal length of the eyepiece is $5\,\text{cm}$, what is the length of the telescope tube?

Which of the following defects of vision is corrected by using a concave lens?

Which of the following is NOT an advantage of a reflecting telescope over a refracting telescope?

A person suffering from hypermetropia uses a convex lens of focal length $50\,\text{cm}$. What is the power of the lens required?