Optics and Light

Lenses form images by refracting light

Refraction of Light As light waves travel through a medium that slows

the wave down, they turn toward the normal (imaginary line perpendicular to the new surface).

Light waves that travel through a medium that speeds up the waves, they turn away from the normal.

Draw diagram of this on page 600 of textbook in the next slide.

Shape determines how lenses form images

A lens is a clear optical tool that refracts light.

Different lenses refract light in different ways and form images useful for a variety of purposes.

Like mirrors, lenses can be concave or convex.

Concave Lenses

Concave lenses are curved inward.Parallel light rays that pass through a

concave lens are refracted outward.The light rays are refracted twice and are

spread out, therefore they do not meet.Draw the concave lens found on page 601 on

the next slide.

Diagram of Concave Lens

* A concave lens causes parallel light rays to spread out.

Convex Lenses

Convex lenses are curved outward. Parallel light rays passing through are refracted

inward and meet at a focal point on the other side of the lens.

The light rays are refracted twice. Draw the convex lens found on page 601 in the

textbook on the next slide.

Convex Lens

A convex lens causes parallel light rays to meet at a focal point.