Light rays are perpendicular to a wave front Light rays are perpendicular to a wave front. A wave front that has traveled a long distance is a plane wave front, and its rays are parallel to each other. The rays show the direction of the wave motion.

Light waves are transverse, so they can be polarized (with vibrations all in the same direction). Light such as an incandescent or fluorescent lamp, a candle flame, or the sun, emits light that is not polarized. This is because the vibrating electrons that produce the light vibrate in random directions. Light is transmitted when the axes of the polarizing filters are aligned, but absorbed when they are at right angles to each other.

Emission: the object itself is a source of light.

Reflection: certain frequencies are reflected from the object, others are absorbed.

(A)Rays reflected from a perfectly smooth surface are parallel to each other. (B) Diffuse reflection from a rough surface causes ray to travel in many random directions.

A particular material absorbs the light frequency that matches the frequency at which electrons in the atoms of that material vibrate.

Opaque, Translucent, Transparent Objects that do not let light pass through them are opaque. Ex. Walls, your desk, the science book Objects that let light pass clearly through them are transparent. Ex. Windows, plastic wrap, eye glass lenses Objects that let only some light pass through are translucent. Ex. waxed paper, frosted glass

Types of Materials Transparent Translucent

FAVORITE EYE? Which eye do you use more? To test which you favor, hold a finger up at arm’s length. With both eyes open, look past your finger to a distant object. Close your right eye. Does your right finger jump to the right? If so, then you use your right eye more. Check this by repeating with your left eye.