Question: Opaque

Answer: Many light sources are opaque which means that we cannot see through them. (Ex: the sun, and tungsten filiment in a light bulb. (The sun is opaque because you cannot see through it.)

Question: What generally happens in a low density gas with photons?

Answer: They typically fly for long distances without encountering other atoms

Question: Atoms in an opaque object

Answer:

Question: Thermal radiation

Answer: The precise shape of the spectrum depends only one thing: the object’s temperature. For this reason, the light emitted by an opaque object is called thermal radiation.

Question: The spectrum of an opaque object does not depend at all on what?

Answer: What the object is made of. Instead, it depends only on the objects temperature.

A lightbulb filing the produces nearly the same spectrum as a star of the same temperature.

Question: Compared to a cold object, a hot object emits most of its radiation at_____ wavelengths and emits____radiation overall.

Answer: Shorter, more

A hotter object emits more total radiation and emits most of it at a shorter wavelengths

Question: The sun has a temperature of 5,800 k(5.8 x10^3 k) in which portion of the spectrum is the intensity the highest?

Answer: Visible.

Most of the radiation emitted by the sun is in the visible portion of the spectrum. This is why our eyes are able to see visible light.

Question: Whenever you listen to the radio you are hearing?

Answer: Sound,Not light

Question: Suppose you go outside and look at three stars. Star A is blue, star b is white, and star c is red. Which star is the hottest and which star is the coldest?

Answer: The blue star is the hottest and the red star is the coldest

Question: Which object emits more infrared radiation?

The earth, the sun, or a star that is the same size as the sun but 5 times hotter?

Answer: A star that is the same size of the sun but 5 times hotter.