Quantum Flashcards
Excitation
When an electron is given enough energy to move up to a higher energy level
Ionisation energy
The minimum energy required to remove the electron from the atom
Explain how a fluorescent tube/ discharge tube works
-mercury vapour at low pressure
-cathode is heated causing thermionic emission
-high p.d. Is applied across the tube
-electrons accelerate cathode to anode
-collide inelastically with mercury atom
-excitation/emission
-photon of UV Emitted
-inner coatings of phosphor atoms absorb UV and emit light
-(cascades down energy levels)
What is the photoelectric effect
When electromagnetic radiation is incident on the surface of a metal, the energy of a single photon is absorbed by a single electron. This electron is then released from the surface. These are called photoelectrons. Energy is conserved in this interaction.
Wave properties
Diffraction and interference
Proof of particle nature
Photoelectric effect
Threshold frequency/wavelength
Minimum/maximum frequency/wavelength of a single photon required to release a single electron from the surface of the metal
Work function Φ
Minimum energy to release an electron from the surface of the metal
hf=
Φ+Ek(max)
Stopping voltage
Minimum p.d required to just stop electrons being emitted from the photocathode
Max kinetic energy of an electron emitted (using V)
Ek(max)= eVs
Diffraction is greatest when
The wavelength and the gap the wave passes through are roughly equal
Proof of wave properties of electrons
Diffracted using a thin crystal onto a phosphor screen
de Broglie wavelength
λ=h/p
eV=
1/2mv^2
