Radiation is energy that comes from a source and travels through space and may be able to penetrate various materials. ... The kinds of radiation are electromagnetic (like light) and particulate (i.e., mass given off with the energy of motion). Gamma radiation and x rays are examples of electromagnetic radiation.

What is the meaning of radiation in physics?

Radiation is energy that comes from a source and travels through space at the speed of light. This energy has an electric field and a magnetic field associated with it, and has wave-like properties. You could also call radiation “electromagnetic waves”.

What is radiation in physics and examples?

Radiation includes emanation of any portion of the electromagnetic spectrum, plus it includes the release of particles. Examples include: A burning candle emits radiation in the form of heat and light. The Sun emits radiation in the form of light, heat, and particles.

What is radiation simple explanation?

Radiation is energy given off by matter in the form of rays or high-speed particles. All matter is composed of atoms. ... In that process, unstable nuclei may emit a quantity of energy, and this spontaneous emission is what we call radiation.

Why do atoms radiate?

Radiation is emitted from atoms when an unstable atom decays to become more stable. When an atom has extra neutrons or protons, it causes the element to become unstable.

What is radiation?

Do atoms emit light?

Atoms emit light when they are heated or excited at high energy levels. The color of light that is emitted by an atom depends on how much energy the electron releases as it moves down different energy levels. ... Absorption is shown by the energy levels increasing as the photon gains energy.

Why do things emit light?

The atoms and molecules that make up matter typically emit light at characteristic energies. ... Stimulated emission occurs when matter in an excited state is perturbed by a photon of light and gives rise to a further photon of light, typically at the same energy and phase as the perturbing photon.

What can alpha penetrate?

Alpha radiation is absorbed by the thickness of the skin or by a few centimetres of air. ... It can pass through the skin, but it is absorbed by a few centimetres of body tissue or a few millimetres of aluminium. Gamma radiation is the most penetrating of the three radiations. It can easily penetrate body tissue.

What is man made radiation?

Man-made (technogenic) radiation sources are any radiation sources produced by humans. They may being produced for use of their radiation, or for other purposes using the processes taking place in them (e.g., production of electric energy or heat).

What does radiation feel like?

The most common early side effects are fatigue (feeling tired) and skin changes. Other early side effects usually are related to the area being treated, such as hair loss and mouth problems when radiation treatment is given to this area. Late side effects can take months or even years to develop.

Why is a burning candle an example of radiation?

Convection draws hot wax vapors out from the wick and sucks oxygen from the surrounding air into the base of the flame. The flame also gives off invisible beams of heat in all directions by radiation.

What is the main form of radiated heat?

Quantum mechanics tells us that thermal radiation involves photons within infrared and visible light frequencies, called thermal radiative rays, which are the basic unit of radiant energy.

What is the emissivity of a black body?

Emissivity is defined as the ratio of the energy radiated from the surface of a material to that radiated from a perfect emitter, known as a blackbody, at the same temperature and wavelength. A blackbody has an emissivity of 1.

What is Alpha beta and gamma rays?

Alpha denotes the largest particle, and it penetrates the least. Alpha particles carry a positive charge, beta particles carry a negative charge, and gamma rays are neutral. ... Beta particles are high energy electrons. Gamma rays are waves of electromagnetic energy, or photons.

Is all radiation harmful?

Not all radiation is harmful, and whether or not it is harmful depends on the type of radiation in question and how much (the so-called 'dose') you are exposed to. Some types of radiation are known as 'ionising'.

How do you explain radiation to a child?

Radiation is energy that moves from one place to another. Light, sound, heat, and X-rays are examples of radiation. The different kinds of radiation fall into a few general categories: electromagnetic radiation, mechanical radiation, nuclear radiation, and cosmic rays.

What is radioactive fuel?

Nuclear fuel is the fuel that is used in a nuclear reactor to sustain a nuclear chain reaction. These fuels are fissile, and the most common nuclear fuels are the radioactive metals uranium-235 and plutonium-239. ... It can also be recycled and used as a fuel in thermal reactors.

Is nuclear fuel man-made?

Nuclear energy can be either natural or man-made. Natural nuclear energy is that which is produced naturally. ... Usually, nuclear energy is produced with the help of a nuclear power plant which makes a controlled atomic chain reaction for producing heat.

What are manmade sources?

Man-made sources include medical uses of radiation, residues from nuclear tests, industrial uses of radiation, television, and numerous other radiation producing devices. For example, in some kind of smoke detectors, you can meet man-made radionuclides such as americium-241.

How is ionising gamma radiation?

Gamma radiation is highly penetrating and interacts with matter through ionisation via three processes; photoelectric effect, Compton scattering or pair production. Due to their high penetration power, the impact of gamma radiation can occur throughout a body, they are however less ionising than alpha particles.

How is ionising gamma?

Gamma rays are very poor at ionising (about 1 to 1) but they are very difficult to stop (they are very penetrating). As they are not good ionisers, they are less dangerous to life.

Why is Alpha the most ionising?

Alpha particles are highly ionising because of their double positive charge, large mass (compared to a beta particle) and because they are relatively slow. They can cause multiple ionisations within a very small distance.

Why does metal turn red when it's hot?

Metals that absorb higher energies will release shorter wavelengths of light (such as blue light) when their electrons return to their ground state. Metals that absorb lower energies will release longer wavelengths of light (such as red light) when their electrons return to their ground state.

Do humans emit light?

The human body literally glows, emitting a visible light in extremely small quantities at levels that rise and fall with the day, scientists now reveal. ... Past research has shown that the body emits visible light, 1,000 times less intense than the levels to which our naked eyes are sensitive.

What is producing light without heat called?

Chemiluminescence - Light without Heat. Many chemical reactions produce both light and heat. ... The light from such reactions is called cool light, because it is created without heat. Reactions that produce light without heat are called chemiluminescent reactions.