Focusing The lens cannot move The closer an object farther away from the moves towards the retina film, the farther the lens must move The ciliary muscles change the shape of away from the film in order to keep the the lens image in focus If an object moves closer to the eye, the muscles make the lens bulge in the middle This bulging is called accomodation Light The coloured iris The diaphragm controls the amount of controls the amount light let in of light let in The opening that lets The opening that light in is called the lets light in is called pupil (is the dark the aperture centre of the eye) Image The retina senses the The image is light and sends focused on the electrical impulses to light-sensitive film the brain through the at the back of the optic nerve camera The light causes chemical changes in the film to record the image Why do most people need to get glasses as they age? Answer: As people get older, their lens stiffens and is not able to change shape when needed in order to focus. This usually affects people’s ability to focus on objects that are near (they become far-sighted) and they would need convex lenses to correct this. Activity and Discussion: Blind spot
Focusing The lens cannot move farther away from the retina The ciliary muscles change the shape of the lens If an object moves closer to the eye, the muscles make the lens bulge in the middle This bulging is called accomodation The closer an object moves towards the film, the farther the lens must move away from the film in order to keep the image in focus Light The coloured iris controls the amount of light let in The opening that lets light in is called the pupil (is the dark centre of the eye) The diaphragm controls the amount of light let in The opening that lets light in is called the aperture Image The retina senses the light and sends electrical impulses to the brain through the optic nerve The image is focused on the light-sensitive film at the back of the camera The light causes chemical changes in the film to record the image Why do most people need to get glasses as they age? Answer: As people get older, their lens stiffens and is not able to change shape when needed in order to focus. This usually affects people’s ability to focus on objects that are near (they become far-sighted) and they would need convex lenses to correct this. Activity and Discussion: Blind spot