Refraction is the deviation of rays of light from their course through the interference of a different medium; reflection is the return of rays of light which, having fallen upon a surface, are repelled by it.
503. What is the radiation of light?
The radiation of light is its emission in rays from the surface of a luminous body.
504. Do all bodies radiate light?
All bodies radiate light; but those that are not in themselves primary sources of light, are said to reflect it.
505. Do black bodies reflect any light?
Black bodies absorb the light that falls upon them. But they reflect a very small degree of light.
506. Why is glass transparent?
Because its atoms are so arranged that they allow the vibrations of light to continue through their substance.