Question

In an astronomical (refracting) telescope, the objective lens has:

Options

• A large focal length only if the object is nearby

• No focal length since it forms a virtual image

• A small focal length and small aperture

• A large focal length

Answer 1

An astronomical (refracting) telescope is used to view distant objects. The objective lens has a large focal length, which allows it to form the image of the distant object at its focus. This image then acts as the object for the eyepiece.