Question

Describe and explain the optics of the microscope and the telescope.

Answer 1

Microscope:

As we all know Microscope is an optical instrument used to view small object. Let us first talk about the simple microscope.

A simple microscope is an optical instrument, we use for the magnification of small objects to get a clear image or vision. It is a convex lens having a short focal length. This microscope is at a small distance from the object for the magnification and hence this forms a virtual image. The simple microscope enables us to view very small letters and figures. Watchmakers also make use of these. Now let us see what compound microscope is.

With a compound microscope, we get very large values of magnification. We use this microscope to see microscopic objects like microorganisms. It comprises of two convex lenses and magnification occurs in both of these lenses. the components of a compound microscope are eyepiece, objective lens, fine and rough adjustment screw.

Telescope:

Telescopes are meant for viewing distant objects and produce an image that is larger than the image produced in the unaided eye. Telescopes gather far more light than the eye, allowing dim objects to be observed with greater magnification and better resolution. Telescopes were invented around 1600, and Galileo was the first to use them to study the heavens, with monumental consequences. He observed the moons of Jupiter, the craters and mountains on the moon, the details of sunspots, and the fact that the Milky Way is composed of a vast number of individual stars.

Figure 2.9.1(a) shows a refracting telescope made of two lenses. The first lens, called the objective, forms a real image within the focal length of the second lens, which is called the eyepiece. The image of the objective lens serves as the object for the eyepiece, which forms a magnified virtual image that is observed by the eye. This design is what Galileo used to observe the heavens.

Although the arrangement of the lenses in a refracting telescope looks similar to that in a microscope, there are important differences. In a telescope, the real object is far away and the intermediate image is smaller than the object. In a microscope, the real object is very close and the intermediate image is larger than the object. In both the telescope and the microscope, the eyepiece magnifies the intermediate image; in the telescope, however, this is the only magnification.

The most common two-lens telescope is shown in 2.9.3b2.9.3b. The object is so far from the telescope that it is essentially at infinity compared with the focal lengths of the lenses, so the incoming rays are essentially parallel and focus on the focal plane.