Content Standard 5 – Contrast ways in which light rays are bent by concave and convex lenses.

Convex lens Remember: Convex lenses bend light rays toward one another.

Convex lenses are thicker in the middle. CONVEX or POSITIVE lenses will CONVERGE or FOCUS light and can form an IMAGE.

CONCAVE or NEGATIVE lenses will DIVERGE (spread out) light rays

How do concave lenses improve your vision if you are nearsighted? If you are nearsighted, your retina is farther away from your lens, so the image is focusing in front of your retina, so you cannot see distant objects. That is when you need a concave lens. Concave lens will diverge (spread out) the light rays onto the retina. Concave Lens

Convex Lens Which one is the concave lens?

A concave lens cause light rays to spread out.

Science Notebook: Draw and label how light travels through a convex lens and a concave lens in your science notebook.

Convex lens make objects appear to be larger (magnify).

LIGHT & ITS USES: Mirrors Reflection & Mirrors (Cont.) Convex Mirror Curves outward Enlarges images. Use: Rear view mirrors, store security… they can show objects spread over a wide area. CAUTION! Objects are closer than they appear! © 2000 Microsoft Clip Gallery

Glasses Convex lens correct farsightedness. Farsighted people cannot see objects that are nearby. Concave lens are used to correct nearsightedness. Nearsighted people cannot see objects that are far away.

How You See Near sighted – Eyeball is too long and image focuses in front of the retina Far sighted – Eyeball is too short so image is focused behind the retina. © 2000 Microsoft Clip Gallery

The correct name of nearsightedness is myopia. Myopia occurs when the eyeball is slightly longer than usual from front to back. This causes light rays to focus at a point in front of the retina, rather than directly on its surface. A concave lens is usually used to correct this problem. Concave Lens

The correct name for farsightedness is Hyperopia. The shape of your eye does not bend light correctly, resulting in a blurred image. A convex lens is usually used to correct this problem. Convex Lens

Good Luck 5 th Graders!