# 31.1 Nuclear radioactivity  (Page 2/12)

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## Alpha, beta, and gamma

Research begun by people such as New Zealander Ernest Rutherford soon after the discovery of nuclear radiation indicated that different types of rays are emitted. Eventually, three types were distinguished and named alpha $\left(\alpha \right)$ , beta $\left(\beta \right)$ , and gamma $\left(\gamma \right)$ , because, like x-rays, their identities were initially unknown. [link] shows what happens if the rays are passed through a magnetic field. The $\gamma$ s are unaffected, while the $\alpha$ s and $\beta$ s are deflected in opposite directions, indicating the $\alpha$ s are positive, the $\beta$ s negative, and the $\gamma$ s uncharged. Rutherford used both magnetic and electric fields to show that $\alpha$ s have a positive charge twice the magnitude of an electron, or $+2\mid {q}_{e}\mid$ . In the process, he found the $\alpha$ s charge to mass ratio to be several thousand times smaller than the electron’s. Later on, Rutherford collected $\alpha$ s from a radioactive source and passed an electric discharge through them, obtaining the spectrum of recently discovered helium gas. Among many important discoveries made by Rutherford and his collaborators was the proof that $\alpha$ radiation is the emission of a helium nucleus . Rutherford won the Nobel Prize in chemistry in 1908 for his early work. He continued to make important contributions until his death in 1934.

Other researchers had already proved that $\beta$ s are negative and have the same mass and same charge-to-mass ratio as the recently discovered electron. By 1902, it was recognized that $\beta$ radiation is the emission of an electron . Although $\beta$ s are electrons, they do not exist in the nucleus before it decays and are not ejected atomic electrons—the electron is created in the nucleus at the instant of decay.

Since $\gamma$ s remain unaffected by electric and magnetic fields, it is natural to think they might be photons. Evidence for this grew, but it was not until 1914 that this was proved by Rutherford and collaborators. By scattering $\gamma$ radiation from a crystal and observing interference, they demonstrated that $\gamma$ radiation is the emission of a high-energy photon by a nucleus . In fact, $\gamma$ radiation comes from the de-excitation of a nucleus, just as an x ray comes from the de-excitation of an atom. The names " $\gamma$ ray" and "x ray" identify the source of the radiation. At the same energy, $\gamma$ rays and x rays are otherwise identical.

$\alpha$ -Particles A sheet of paper, a few cm of air, fractions of a mm of tissue
$\beta$ -Particles A thin aluminum plate, or tens of cm of tissue
$\gamma$ Rays Several cm of lead or meters of concrete

## Ionization and range

Two of the most important characteristics of $\alpha$ , $\beta$ , and $\gamma$ rays were recognized very early. All three types of nuclear radiation produce ionization in materials, but they penetrate different distances in materials—that is, they have different ranges . Let us examine why they have these characteristics and what are some of the consequences.

explain how a light wave can be propagated in accordance with the principal of reversibility
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Chibuzo
the definition of photon
8kg of a hot liquid initial T is 90°© is missed with another liquid 3kg at 20° calculate e équilibrium T
8kg of a hot liquid initial T is 90°© is missed with another liquid 3kg at 20° calculate e équilibrium T
Balki
Bright
what are the products when acid and base mixed?
Austin
salt and water
michael
michael
salts and water
Roben
i guess salt and water
Chibuzo
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work done is the product of force and distance moved in the direction of force
Work done = force (F) * distance (D)
abdulsalam
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Abdul
y
Tracy
explain the three laws of isaac Newton with the reference
1st law ; a body will continue to stay at a state of rest or continue to move at a uniform motion on a straight line unless an external force is been acted upon
Austine
3rd law; in every action there is an equal or opposite reaction
Austine
2nd law: F=ma
Austine
what is circut
newtons law of motion
hasiya
First law:In an inertial frame of reference, an object either remains at rest or continues to move at a constant velocity, unless acted upon by a force.
Manan
a circuit is an electric part Wich is linked by a wire
Chibuzo
is the ability to do work
Energy
Nwany
u from
Hejreen
any body online hain
Hejreen
ability to do work is energy
energy
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what is energy
energy is ability of the capacity to doing work
shafiu
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A quantity that has both magnitude and direction
Donaldo
can a body with out mass float in space
mosco
Is the quantity that has both magnitude and direction
Amoah
Yes it can float in space,e.g.polyethene has no mass that's why it can float in space
Amoah
that's my suggestion,any other explanation can be given also,thanks
Amoah
A charge of 1.6*10^-6C is placed in a uniform electric field in a density 2*5^10Nc^-1, what is the magnitude of the electric force exerted on the charge?
what's phenomena
Phenomena is an observable fact or event.
Love
Prove that 1/d+1/v=1/f
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What is a polarized light called?
Moyinoluwa
what is a half life
the time taken for a radioactive element to decay by half of its original mass
ken
mohammed
Half of the total time required by a radioactive nuclear atom to totally disintegrate
Justice
radioactive elements are those with unstable nuclei(ie have protons more than neutrons, or neutrons more than protons
Justice
in other words, the radioactive atom or elements have unequal number of protons to neutrons.
Justice
state the laws of refraction
Fabian
state laws of reflection
Fabian
Why does a bicycle rider bends towards the corner when is turning?
Mac
When do we say that the stone thrown vertically up wards accelerate negatively?
Mac
Give two importance of insulator placed between plates of a capacitor.
Mac
Macho had a shoe with a big sole moving in mudy Road, shanitah had a shoe with a small sole. Give reasons for those two cases.
Mac