OPAQUE MATERIALS

Date: 2015-10-07; view: 439.

Materials that _______ light without reemission and thus allow no light through them are opaque. Wood, stone, and people are ________. In opaque materials, any coordinated vibrations given by light to the atoms and molecules are turned into random _______ ______ – that is, into internal energy. The materials become slightly _______.

Metals are also opaque. Interestingly enough, in metals, the outer electrons of atoms are not bound to any _________ ____. They are free to wander with very little restraint throughout the ________. That's why metals ________ electricity and heat so well. When light shines on metal and sets these free electrons into vibration, their energy does not ‘spring' from atom to atom in the material but is reemitted as ________ _______. This reemitted light is seen as a _________. That's why metals are shiny.

Our atmosphere is _________ to visible light and some infrared, but fortunately, almost opaque to high-frequency ___________ ______. The small amount of ultraviolet that does get through is responsible for _________. If it all got through, we wouldn't dare go out in the sun without protection. Clouds are __________ to ultraviolet, which is why you can get a sunburn on a cloudy day. Ultraviolet also _________ from sand and water, which is why you can sometimes get a sunburn while in the shade of a beach umbrella.

Exercise 13. Complete the table using the information from the texts.