If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content

Unit 9: Ray optics and optical instruments

About this unit

Light waves can be bent and reflected to form new and sometimes altered images. Understanding how light rays can be manipulated allows us to create better contact lenses, fiber optic cables, and high powered telescopes. In this unit, let's learn about reflection, refraction, defects in the human eye and the lenses we use to correct them, and optical instruments such as the microscope and telescope.