Light Manipulation Using Telescopes As91169

Light Manipulation using telescopes AS91169 (begin writing below the heading)

Refraction is when light changes speed as it travels from one medium to another, causing it to bend. This is because the optical density of the medium differs depending on what the medium is. The word medium is used to describe regions that will allow light waves to pass through it. A few examples of mediums would be air, glass, and water. Light can travel through all of them but, due to the different optical density of the mediums, not at the same speed. The more optically dense the medium is the slower light will travel through it, and the less optically dense the medium is the quicker the light will travel through it. A way to measure the optical density of a

The objective lens is positioned near the front of the telescope, it is the larger lens of the two and is convex with a long focal length to provide the immense magnification required to see objects in from far distances. The eyepiece lens is placed at the end of the telescope, it is a smaller (than the objective lens) convex lens (concave can be used as well most eyepieces are convex) with a short focal length used in order to focus the rays of light back into seemingly parallel rays providing a clear image. The focal length will vary on different lenses in different telescopes. Descartes Law provides a mathematical relationship between the focal length and positions and sizes of the object and image. The equation 1/f = 1/do + 1/di tells us that the focal length (f) is equal to 1 divided by the distance from the object to the lens (do) + 1 divided by the distance from the image to the lens (di). This equation can be rearranged to give us the do provided the focal length and di are given and vice versa. After the do and di are found the magnification of the image can be calculated using di/do. When the rays of light enter the objective lens, they converge towards the normal line due to the different mediums between air and glass. When the light exits the lens it converges once again towards the normal line. Although light bends twice it is simplified in diagrams being drawn with one

This is because of the lenses used in the telescope, causing the rays to invert by converging them so much. The light rays start off by travelling into the objective lens. The lens then bends them towards the normal line causing them all to meet at the focal point, forming an image which is; diminished, inverted, and real. The image is real because the rays forming the image are real rays. The rays from this image converged by the objective lens continue on to the eyepiece lens, which again converges them towards to the normal line making them back into parallel rays, but inverted. These rays continue forward until they meet the observer's eye, which also has a convex lens. This lens is special and can bend to fit the image into our eye. Just like the objective and eyepiece lens, our eye bends the rays so they all meet at a point in our eye called the retina. The image formed at our retina is inverted, but since telescopes are usually used to look into space, and space has no up and down, the image usually isn’t affected by being inverted.This diagram puts what was just explained into a visual. The rays travelling through the objective lens, through the focal point, inverting through the eyepiece lens, through the lens in the eye, and forming in the retina. Once again the formula 1/f = 1/do + 1/di can be used to calculate where the image will