Matter & Radiation

The Atom

Isotopes- Atoms of the same element with a different number of protons but the same nuber of neutrons
Specific Charge= Charge/Mass
an electron has the largest specific charge (-1.60x10-19/1.67x10-27)
the strong neuclear fource has a range of about 3-4fm (x10-15)has the same effect on protons and neutrons and is an attrctive ource at 3-4fm but a repulsive fource at 0.5fm
Alpha Radiation (α)-This is a helium atom the decay can be represented like this
Beta Radiation( )-Is a fast moveing electron when a neutron changes to a proton ina nucleus it can be represented like this
Gamma Radiation( )-This is electromagnetic radiation emmited by an unstable nucleus it has no mass or charge it is emmited after alpha or beta decay

1 of 4

electromagnetic waves are emmitted by a chargd particle that loses energy they are emmitted in short "bursts"
each packet of energy that is emmitted is called a a Photon the photon theory was established by einstein in 1905 to explain the photoelectric effect
E=hf
Laser Power- Power=nhf

(http://micro.magnet.fsu.edu/primer/java/electromagnetic/electromagneticjavafigure1.jpg)

2 of 4

Anti -Matter was predicted in 1928 by Paul Dirac he predicted that
A)They annihilate each other when they meet converting there mass into photons
B)They have the same rest mass as each other
C)They have the exact opposite charge as each other
he also predicted pair production in which a photon (with enought energy)would change into a partcle anti partcle pair
the discovery of the positron- he found that the trails left by the electron and positron were exactly the same but in different directions

3 of 4

Electro Magnetic Fource-electro magnetic fource between two cgarged objects is due to the exchange of virtual photons
The Weack Nuclear Fource-Responsible for ANY type of Decay
Electron Capture-a proton in a proton rich nucleus may change into a neutron due to this an electron will be released

4 of 4