When light travels to a new medium its speed and direction will change, this is called refraction. Materials have different optical density so light rays travel at different velocities. Refractive index is the ratio of the speed of light in a vacuum to the speed of light in a medium. Calculated by the velocity of light in vacuum divided by velocity in a medium. If a medium has a high refractive index ( more optically dense) the more the light will be slowed by the transparent substance.
When light travels through a less optically dense medium, it speeds up and moves away from the normal line. This …show more content…
The bigger the aperture of the lens the more light it collects. They allow objects from a distance to become magnified, clearer, and brighter. Most Refracting telescopes use two main lens, the objective lens, which is a convex lens that are thicker in the middle than the edges for different refraction of light and goes at one end of the tube, and the eyepiece for viewing, on the opposite end, which is also a convex lens. Light moves from air to glass, which is more optically dense, and slows down and bends towards the normal, when light travels out of the lens, it speeds up and moves away from the normal. Convex lenses are also called converging lens because they produce converging rays with real focal point. The size and thickness of convex lens alter the focal length. So the fatter the lens, the shorter the focal length. The focal length is measured in positive units for convex …show more content…
The formula for magnification is M=(fo/fe), where fo is the focal length of the objective lens, and fe is the focal length of the eyepiece. This means the size of an image is proportional to the focal length of the lens. So the longer the focal length of the objective lens, or shorter the focal length of the eyepiece, increases the magnification.
In refracting telescopes, the objective lens will always be the largest lens of the two. The objective lens is larger so it can collect more light than the human eye could. Increasing the diameter of the objective lens allows more light to be collected. The eyepiece of the telescope then focuses all the light collected into a small area suitable for viewing by the eye.
Magnifying objects from a distance might seem to use to telescopes, but the quality of the image is affected by the earth’s atmosphere. So magnifying a blurred image does not make it clearer and sharper. Telescopes are designed so it gathers more light, plus making them brighter and clearer to see faint details. The brightness of an image also depends on how much light is collected by the objective lens. It is proportional to the area of the lens. Increasing the area means increasing the size of the lens so more light can be collected and brighter the image. Brightness also depends on the area of the eyepiece. The eyepiece is designed small to make the images