# Lens

There are two lenses:

- The concave lens is used to refract light beams and rays in a way which spreads them out.
- The convex lens is used to refract light beams and rays in a way which bends them inwards.

Tips for use:

- Use a lens in conjunction with an object marker to create ray diagrams.
- There are 'hotspots' at the centre of the lens and the focal point. Measurement parts such as the ruler will snap to these hotspots to let you measure key lengths.
- You can change the focal length in-scene using the resize handles.

## See also:

- Forming an image
- Forming a ray diagram
- Object marker
- Using Optics parts