Physics Unit 1 A level AQA

Nucleus: Found in the centre of an atom and is composed of protons and neutrons.

Nucleon: A particle found in the nucleus i.e. proton or neutron.

Nuclide: A type of nucleus with a particular number of protons and neutrons.

Isotope: An atom which has the same amount of protons but a different amount of neutrons.

Specific Charge: This the charge of a particle which can be defined as its charge divide by its mass; C/M.

Proton:

Charge: 1.6*10^19 (units C)

Mass: 1.6*10^-27 (units Kg)

Neutron:

Charge: 0 (units C)

Mass: 1.6*10^-27 (units Kg)

Electron:

Charge: -1.6*10^-19 (units C)

Mass: 9.7*10^-31 (units Kg)

Do not decay

This is due to a strong nuclear force holding the particles together

This strong nuclear force overcomes the electrostatic repulsion

It is the strong nuclear force which holds the neutrons and protons together 

Range: 3-4 femtometres (units fm and is 10^-15 metres)

The effective range of the  strong nuclear force  is approximately the size of a small nucleus.

Between 3-4 femtometres the  strong nuclear force  acts to attract the nucleons But at separations which are closer than 0.5 femtometres it acts repulsively.

Alpha (a) – an atom decays into a new atom and emits an alpha particle;          (2 protons and 2 neutrons – the nucleus of a helium atom)

Beta (b) – an atom decays into a new atom by changing a neutron into a proton and electron.  The fast moving, high energy electron is called a beta particle.

Gamma – after a or b decay surplus energy is sometimes emitted as an atom  rearranges its electrons.  This is called gamma radiation and has a very high frequency with short wavelength.  The atom is not changed.

Gamma is EMR with no mass or charge.

It is emitted after either alpha or beta emission if has too energy.

1eV is defined as the energy transferred by an electron when it is moved thorugh a potential difference of 1 volt.

Speed of Light = 3x10^8

Energy of a photon = h x f (Plancks constant x Frequency)

Power = n x h x f ( where n is the number of photons; nhf)

Intensity= Amount of energy transfered per second

All objects emit infrared radiation

Wavelenghts are always expressed in nanometres (x10^-9)

V= f x Lamda  => C= f x Lamda

Photon Energy = h x f