Refraction Of Light Lens

We are only able to see due to the fact that light from an object travels from the said object and into our eyes.When a ray of light passes through different mediums, it changes both the velocity of the light ray and the direction.This is called the refraction of light rays. This is due to the fact that different substances have different optical densities. The light will travel slower through a substance that is very optically dense and faster through one that is less dense. The refraction of a ray of light only occurs at the boundary line and light rays always travel in a straight line. Refraction does not occur when the object is at an angle of 90 degrees and only occurs when the object is tilted. When a light ray hits the boundary line

Lenses are used in telescopes to help view very small items that are at far distances away. They do this by refracting incident light rays as they reach the boundary and then refracting them again as to form images. A lens produces this image because the light waves will travel more slowly in the lens rather than in the air and refraction occurs.There are many differentiations between types of lenses. The main lenses in telescopes are converging/convex and concave/diverging lenses. A converging lens converges rays of light at a point that is parallel to its principal axis. It also focuses the light rays at the focal point. The converging lenses produce real images and also enables objects to be magnified from their original size. For converging lenses, the incident rays that travel through the lens will refract and diverge the light waves away from the principal axis. The incident rays that travel parallel to the principal axis and then into the lens will travel through the focal point on the other side. The diagram below shows this diverging of light rays. The light rays will only intercept with each other on their incidence side and not on the other side of the lens. The image formed from concave lenses is virtual. Images can appear smaller when viewed through concave

These telescopes do this by refracting the light rays that enter the telescope through the lenses. The light will travel through the objective lens and down the telescope where it will reach the eyepiece lens and will be magnified. Refracting telescopes produce real images that are diminished from the original object. The objective lens will collect the light from objects that are far away and will bring it to the focal point. The eyepiece will then collects the light from the focal point and spread it out so that the image looks larger. The final image produced is upside down(Inverted) and as light moves in all directions, the only light rays that are seen through the telescope are the ones going in the direction of the lens. The focal length will change depending on the strength of the telescope. The size of the image produced is also proportionate to the size of the lens. This is because if the lens is larger, it can gather more light and therefore more of the image. This will also affect the brightness of the image produced. The magnification of the image is proportionate to the ratio between the focal length of the object and the focal length of the eyepiece lens. The amount of light that can be gathered is increased by 4 times if the diameter of the lens is doubled. The Descartes formula can be used to find out the location and magnification of the image formed.