Lenses form images by refracting light. There are two main types of lenses converging and diverging and they have opposite effects on light rays.
- A converging lenses is convex- causing parallel light rays to converge at the principal focus.
- A diverging lenses is concave- causing parallel light rays to diverge.
- The axis of a lens is a line passing through the middle of the lens.
- The principal focus of a converging lens is where light rays parallel to the axis meet.
- The principal focus of a diverging lens is the point in which the light rays parallel to the axis appear to all come from- where you can trace them back to untill the appear to meet up behind the lens.
- There is a principal focus on each side of a lens. the distance from the center to the principal focus is called the focal length.
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