- #1
philrainey
- 90
- 0
is it true that the radiation a colder body radiates through a vacuum will never hit a hotter body and have its radiation energy absorped? Is the radiation simply one way from the hot body to the colder body?
In summary, the radiation from a colder body through a vacuum can hit a hotter body and have its energy absorbed. However, the net transfer of energy is still from the hotter body to the colder body. Both bodies emit radiation towards each other and into outer space, but the colder body receives more radiation from the hotter body than it emits back. Therefore, the colder body is still the net receiver of energy.
- #2
tiny-tim
Science Advisor
Homework Helper
- 25,839
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Hi philrainey! 
Nooo … they both absorb radiation from each other …
but the colder body always wins!
philrainey said:
Nooo … they both absorb radiation from each other …
but the colder body always wins! - #3
DieCommie
- 157
- 0
Remember that the hot emits more than the cold. So in the end there is still a net transfer from hot to cold, not from cold to hot.
- #4
russ_watters
Mentor
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The wording of the first sentence is very unclear to me...
Are you asking about two bodies sitting near each other in space? The hot object will radiate toward the cold one, but both will radiate away into space. Depending on the specifics of the situation, the cold one may still have a net loss of energy. Ie, the planets in the solar system have lost energy and cooled over billions of years despite getting energy from the sun. They radiate away more than they receive.
Are you asking about two bodies sitting near each other in space? The hot object will radiate toward the cold one, but both will radiate away into space. Depending on the specifics of the situation, the cold one may still have a net loss of energy. Ie, the planets in the solar system have lost energy and cooled over billions of years despite getting energy from the sun. They radiate away more than they receive.
- #5
philrainey
- 90
- 0
russ_watters said:
From what I understand you are right that hot body radiates heat to the cold body and both radiate to outerspace but the cold body also radiates a little portion of heat to the hot body but not as much as the hot body to the cold one.
- #6
russ_watters
Mentor
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Oh, well yes, it can be said that the cold body radiates toward the hot body and just receives more in return, yes. The net effect is it is receiving.
1. What is radiation?
Radiation is the emission of energy in the form of waves or particles. It can come from natural sources, such as the sun, or human-made sources, such as X-rays.
2. How does radiation affect living organisms?
Radiation can have both beneficial and harmful effects on living organisms. Small doses can be used for medical purposes, such as X-rays for imaging, but high doses can damage cells and cause health problems.
3. What are the different types of radiation?
The three main types of radiation are alpha, beta, and gamma. Alpha particles are the least penetrating and can be stopped by a sheet of paper, while beta particles can be stopped by a few millimeters of aluminum. Gamma rays are the most penetrating and require several inches of lead or concrete to shield.
4. How is radiation measured?
Radiation is typically measured in units of absorbed dose, which is the amount of radiation energy absorbed by a material, and equivalent dose, which takes into account the type of radiation and its potential damage to living tissue. These measurements are usually expressed in units of gray (Gy) or sievert (Sv).
5. How can we protect ourselves from radiation?
Some common ways to protect ourselves from radiation include maintaining a safe distance from sources, limiting exposure time, and using protective equipment, such as lead aprons or shielding. It is also important to follow safety guidelines and regulations set by authorities.
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