Define radiation.?

Question

i've looked on the internet and found heaps of definitions for radiation but i don't really undsand them and they all say different theings. Can someone explain radiation and how it works so i can understand it. Thanx.

Answer 1

OK, I will confuse the issue further. Much further.  

   In the 1920's Einstein and his contemporaries realized that radiation - all of it - was a quantum effect. That all forms of radiation were the emission of mass-less packets of energy they named photons.

Photons, they found, were emitted when an electron changed its energy state downwards, when it lost energy. And   photons cease to exist when they transfer their energy to an electron, when the electron goes to a higher energy state.

  The core of the confusion, of the problem is that Quantum Mechanics is very VERY complicated, and so, even though it is admittedly the most tested and verified theory in the history of physics, few people really understand it. Fenyman, a man very involved in its developments in the 1940's thought no one really understood it.

   And since effectively, no one does common radiation calculations using quantum mechanics - people use the older wave equations instead -  when asked a theoretical question, people revert to this admittedly easier explanation.

  But quantum mechanics was developed exactly because the wave idea did not explain too many things, and QM does, and exceedingly well. So for now, at least, as it has been for the past 90 years or so, radiation is an emission of particles of energy: of photons.

By the way, I notice that you do not pick 'best answer' for the questions you ask. Many people, like the other people who have contributed to this question, spend their time and sincere energies trying to answer your question.

  It is really a courtesy to acknowledge that you have read and appreciated these efforts, and picking the best answer is the only way you can do that. Also, if you do not pick a correct answer, then it sometimes happens that the silliest answer is chosen as best.  It is, of course, your call which answer you pick, but do make the effort to pick one.

Answer 2

I hate to add anything to what Steve said as he looks like he knows what he is talking about. Let me give you a general definition as it is used today.

Radiation is the transfer of energy from one point in space to another. It is NOT (common scientific use) JUST the transfer of energy in the electromagnetic spectrum, although that of course is also radiation.

If energy is being transferred (eg. sound, heat, light) through space, it is called radiation. There are two main types of radiation that are commonly talked about: ionizing and non-ionizing. Ionizing is dangerous as it has high enough energy to remove electrons from atoms! This can cause unwanted chemical reactions in your body (eg. carcinogenesis, or cancer). Non-ionizing radiation (radiowaves, sound, etc) are generally not considered as dangerous although they can cause heating effects in biological tissue (microwaves for example), if the power is high enough. The exact mechanisms for how "radiation works" depend on what type of radiation you are talking about. EM radiation is fundamentally photons ("light") carrying energy from one point in space to another. Sound and heat have more to do with the transfer of vibrational or thermal (motion) energy to molecules or atoms.

Answer 3

Radiation is a fluctuating electromagnetic field.

Imagine an electromagnet turning on and off.  Its field builds, then collapses.  The rate at which it turns on and off is the frequency of the radiation.  The frequency determines the characteristics of the radiation.

The different types of radiation listed by bill above give an idea about how diverse these characteristics can be.

Hope this helps.

Answer 4

There are many many different kinds of radiation, perhaps you can be more specific?

light

infrared

ultraviolet

radio

long wave

short wave

gamma rays

X rays

microwaves

LF

ULF

.