Telescopes magnify distant objects.
Magnification allows distant objects to appear closer and small objects to appear larger. Telescopes are an important visual aid in seeing distant objects on the ground and in the sky. Microscopes reveal the hidden world that surrounds us. The image produced by these instruments is substantially larger than the objects appear without the aid of these means. This ratio of object to image is defined by magnification. A magnification of ten means an object appears ten times larger using the instrument than without. The magnification of images in telescopes and microscopes can be determined by the lenses (or mirror) used in the instruments.
Instructions
Telescope Magnification
1. Determine the focal length of the objective mirror (or lens). The focal length is the distance from the lens or mirror where the light rays converge. Most manufacturers list the focal length in the lens specifications. Refracting telescopes use an objective lens while reflecting telescopes use an objective mirror. In either case, the objective collects the light and focuses it toward the eyepiece. In refracting telescopes the objective lens is located at the end of the telescope tube away from the observer. The objective mirror in reflecting telescopes is located at the bottom of the telescope tube.
2. Determine the focal length of the ocular lens in the eyepiece. The eyepiece is the portion of the telescope the observer looks through.
3. Divide the focal length of the objective mirror (or lens) by the focal length of the eyepiece. The quotient is the magnification of the telescope. For example, if the focal length of the objective mirror in a a reflecting telescope is 1000 millimeters and the eyepiece focal length is 10 millimeters, then the magnification of the telescope is 100x (1000 mm / 10 mm = 100x).
Microscope Magnification
4. Identify the magnification of the ocular lens. The ocular lens is located in the eyepiece of the microscope. The magnification is usually engraved on the eyepiece.
5. Identify the magnification of the objective lens. The objective lens is located on the nosepiece of the microscope. Most compound microscopes have a nosepiece that allows different objective lenses to be rotated into use. It is important to note which objective lens is being used. This is the lens directly over the specimen on the stage. Magnification is usually engraved on the side of the objective lens.
6. Multiply the magnification of the ocular lens by the magnification of the objective lens. The product is the total magnification of the microscope. For example, a 10x eyepiece with a 40x objective lens would produce a magnification of 400x (10 x 40 = 400).
Tags: focal length, objective lens, objective mirror, ocular lens, distant objects
