Theoretically false. An object at the temp of absolute zero would emit no energy or radiation. However, absolute zero does not exist in nature (as far as we know), therefor, in a practical sense the statement is true.
With rare exceptions, all objects will both emit and absorb energy. There is a good correlation between the emissivity of a substance, and its absorption. A flat black surface will be both a good emitter and a good absorber of energy. A shiny surface will be poor for both emission and absorption.
But substances do not necessarily emit at the same wavelengths as they absorb. For example, when illuminated by white light, a red ball will only reflect the red wavelengths. All other wavelengths are absorbed. Light is a form of energy.
Depends on the radiation you are talking about:
They can do it either thermally as wideband blackbody radiation or as an antenna which may operate either narrowband or wideband or as very narrowband excited states.
Blackbody radiation/absorption is always omnidirectional.
Antenna radiation/absorption can be either omnidirectional or concentrated in one or more directional lobes depending on the structure of the antenna.
Excited state radiation/absorption can be either omnidirectional or highly unidirectional; if the excited state is a molecular vibrational or rotational state the radiation/absorption line can be anywhere in the radio frequencies, if the excited state is in the electron orbitals the radiation/absorption line can be anywhere from microwave frequencies to x-rays depending on the energy difference between the orbitals, if the excited state is in the nucleus the radiation/absorption line will be in gamma rays. MASERs and LASERs are highly unidirectional sources of electromagnetic radiation that make use of excited states.
All objects emit electromagnetic radiation
Yes, it happens all the time. Objects on Earth get heated up by the Sun, and naturally they also emit electromagnetic radiation, according to their temperature.
the energy
Most sources of radiant energy, like the sun or lightbulbs, also emit thermal energy, which is heat.
In the form of visible and infrared light from the fire.
No, not equallyNo. There's a lot of variation.
Electrons can absorb photons and gain energy, and they can emit photons and lose energy.
All object at any temperature irradiate radiation, yet, net total energy may be in minus.In example, earth do reflect and irradiate energy to the sun but in total we recieved energy from the sun at approx 1400 W/m2
Yes.
Radiant energy is a term that is almost exclusively used for electromagnetic energy. When something is hot, it emits radiant energy. The sun is an obvious example, but all object actually emit radiant energy. The hotter the object, the more energy. Sound does carry energy, but it is not electromagnetic. Objects can emit sound and even "radiate" sound, but the term radiant energy is not normally used for sound.
Most sources of radiant energy, like the sun or lightbulbs, also emit thermal energy, which is heat.
In the form of visible and infrared light from the fire.
No, not equallyNo. There's a lot of variation.
The pupil does not absorb anything, it transmits light energy to the retina at the back of they eye, the retina does the absorbing. It certainly does not emit anything either, though aliens in scifi films can have glowing eyes! Some animals like cats have reflective eyes, but they are not emitting light, only reflecting incident light.
All substances above absolute zero emit radiant energy. Whether the object emits more than it absorbs depends on its temperature compared to the temperature of its surroundings. An object warmer than its surroundings will usually be a net emitter.
No, not equallyNo. There's a lot of variation.
As an outcome of nuclear fusion of sun light elements ofDeuteriumand tritium
because it can absorb and re-emit the suns energy
because it can absorb and re-emit the suns energy
All object at any temperature irradiate radiation, yet, net total energy may be in minus.In example, earth do reflect and irradiate energy to the sun but in total we recieved energy from the sun at approx 1400 W/m2