does an object that absorbs radiant energy well also emit radiant energy well?

Answer 1

yes.
what you say is 100% true for simple materials.
but if the energy absorbed is utilized for other purposes like generating potential difference(solar panel) then its not true..

for illustration consider a perfectly black body:
according to planck's law of black-body radiation it will be the best absorber as well as the best emitter of heat.

Answer 2

If an object is in thermal equilibrium with the background then the absorption equals emission, or the object would cool/heat, which violates the laws of thermodynamics. This hold true for each individual wavelength if incident radiation has a black body spectrum. The case of interest is usually sunlight on object much colder than the sun. What matters then in the absorption at the wavelengths where the sun emits most of its energy, and the emission of the object at the objects temperature. By choosing the right coating the temperature of satellites can be controlled. It is also an important factor in determining the earths temperature.

Answer 3

A body that is a good absorber of certain rays is also a good radiator of these rays and vice versa.

The temperature of water coated with sliver rise slowly, and, the temperature of water in a dark flask rise rapidly, under the action of solar rays.

In the first case there is little absorption of solar energy, while in the second there is considerable absorption.

Now, let us assume both vessels are filled with hot water and placed in a refrigerator. The water in the dark flask cools much more rapidly since the better absorber is also a better radiator.

Another striking experiment may be performed with colored ceramic. If the color of the body is green, it will not absorb green light. It will absorb a light complementary to green. Thus, if we heat it, it is seen that it begins to assume a color complementary to green. The better absorber is also a better radiator.

Answer 4

Yes, unless it is a "selective surface".
A flat black surface, for example, will absorb about 96% of the energy, reflect back 4% without absorbing it. Green paint will absorb about 50%, reflect back 50% without absorbing it. Both surfaces will re-radiate what they absorbed at about the same rate that they absorbed it at.

A "selective surface" is a coating designed to absorb, but not radiate. This coating was invented by Everett Barber for use in solar collectors, and was about the single most important advance for flat plate solar in the last 50 years. With it the double glazing needed before to minimize heat loss was not needed, which reduced weight, cost and improved efficiency. Selective surfaces absorb about 90%, and radiate about 10%.

Answer 5

All objects (above absolute zero) emit radiation.

A. Higher temperature: the maximum emission of radiant energy occurs at shorter wavelengths (sun ~ 0.5um)

B. Lower temperature: the maximum emission of radiant energy occurs at longer wavelengths (earth ~ 10um)

Answer 6

That would depend on whether the object used or reflected the energy. example: the Hubble space telescope, it absorbs well, but uses what it absorbs.

Answer 7

Not necessarily. Case in point: the ceramic tiles on the space shuttle. They're designed to absorb heat like there's no tomorrow, yet they're also designed *not* to reradiate it. Thus, they can get glowing orange hot, but if the corners are grey, you can pick it up with your hand.