Physics Unit 1

Electrons in atoms can only occupy certain energy levels, the ground state is the lowest energy state an electron can occupy. The electrons collide with the orbital electrons, giving them the energy necessary to move to a higher energy level. Electrons later return to the ground state, loosing energy by emitting photons of different frequencies depending on energy difference.

The minimum energy needed by an electron to escape from the surface.

E=hf

Electrons can have wave like properties and particle like properties

The kinetic energy of released electrons increases, this is because increasing the frequency of the photons increases their energy.

The number of electrons emitted increases because there are now more photons striking the metal surface

Experiment needs to b performed, the results need to be proved

5.5eV does not have enough energy to excite an electron.9.0eV provides enough energy to excite an electron.

Fluorescent tubes contain mercury vapour, across which a high voltage is applied. When electrons in the mercury collide with fast-moving free electrons, they're excited to a higher energy level. When these excited electrons return to their ground state, they emit photons in the UV range. A phosphorus coating on the inside of the tube absorbs these photons, exciting its electrons to much higher orbitals. These electrons then cascade down the energy levels, emitting many lower energy photons in the form of visible light.

Plank Constant

A helium nucleus

Work function is the minimum energy needed to release an electron, below a certain frequency energy of photon is less than work function

Hf is the energy available so energy to remove the electron varies

Joules

Diffraction