Video and lesson investigations on the topic of lenses. Key concepts include:
- Magnifying lenses and microscopes help in seeing small things.
- Binoculars and telescopes help in seeing distant areas or objects.
- There are special devices to help us see in the dark or inside the body.
- Many aids to vision use lenses.
- Lenses can have the effect of enlarging the view of an object.
- Lenses can also have the effect of bringing a distant object closer.
- Lenses come in two basic shapes; concave and convex.
- Concave lenses are thin in the middle and thick at the edges, and spread out the rays of light that pass through them.
- This makes objects appear smaller or further away than they are.
- Convex lenses are thick in the middle and thin at the edges.
- They converge rays of light and make objects appear larger or closer than they are.
- Focusing is important when using lenses.
- X-rays can show bone but not skin and flesh.
- Infra-red viewfinders enable objects to be seen in the darkness.