11. Modern Physics

The emission of electrons from the surface of a hot metal

Streams of high speed electrons moving from the cathode to the anode

The energy gained or lost by an electron when it moves through a potential difference of 1 V.

1 eV = 1.6×10^-19 J

The release of electrons from the surface of a metal by electromagnetic radiation of a suitable frequency

For a given metal is the minimum frequency needed for photoemission to occur

Of a metal is the minimum energy needed to remove an electron from the surface of the metal

A packet / bundle of Electromagnetic radiation

High frequency electromagnetic radiation

Specific frequencies of electromagnetic radiation emitted by an element.

of an element is the number of protons in the nucleus. (Z)

of an element is the total number of protons and neutrons in the nucleus. (A)

Atoms of the same element that have the same number of protons but different number of neutrons

The decay of unstable nuclei with the emission of one or more types of radiation

Fast moving helium nuclei ejected from the nuclei of radioactive atoms

High speed electrons ejected from the nuclei of radioactive atoms

High frequency electromagnetic radiation emitted from the nuclei of radioactive atoms

Loss or gain of an electron

The activity of a radioactive sample is the number of nuclei decaying per second

1 Becquerel is equal to 1 disintegration per second

The activity is directly proportional
to the number of nuclei present

The time taken for half the nuclei to decay.

The breaking up of a large nucleus into two similar sized nuclei with the release of energy and neutrons.

The joining of two small nuclei to form a larger nucleus with the release of energy.

Neutrons from one reaction initiate subsequent reactions