Overhead projector

           Overhead projector is a variant of slide projector that is used to display the images to an audience. For example teacher can use this technology to show to all student in class. An overhead projector typically consist of a very bright lamp or a fan that is use to cool it. On top of the box is the large lens that coolimates the light. On the long arm that is on the top of the overhead projector is a mirror and lens that focus and redirect the light forward. Transparencies that we want to display to student can be put on top of the lens for the purpose of display. The mirror allow the presenter and the audience to see the image at the same the presenter looking at transparencies during writing. The height of the mirror can be adjusted. The purpose is to focus the image and also ,make the image larger or smaller depending on how close the projector is to the screen

        Better quality overhead projector offer an adjustment wheel or screw on the body of the projector to move the lamp away from the lens. If the mirror above the lens is move too high or too low ,it will move out the best focal distance for evenly white image, resulting in a project image with either blue or brown color outside the screen. Turning the adjustment wheel move the lamp to correct the focal distance and restore all the white project image.

        Overhead projector facilitate an easy and low cost but interactive environment for educator. Teaching material can be printed on plastic sheet,where the educator can directly write using the non permanent washable marking pen. This save time for educator. This transparencies also can be use repetitively rather than having material with manually written on the board before the class. The overhead is typically placed at a comfortable height that is suitable for educator and allow the educator to face the class at the same time. This will facilitating better communication between the student and the teacher. The projector can enlarge the feature shown, where this allow the educator to write in a comfortable small script like in the natural writhing position rather than have to write in overly large script on blackboard beside can avoid the teacher to hold his arm in midair just to be able to write on the blackboard. During teaching,when the transparencies sheet is full of written or drawn material,it just can simply be replaced with new fresh sheet with more printed material. This can saving class time rather than use blackboard that would need to be erase and the teaching material have to be rewritten again. Following the class period,the transparencies are easily restored to their original unused state by washing off with soap and water.