Flashcards in Particles And Waves Deck (38):
What are force mediating particles called?
What are the three types of bosons?
W and Z bosons
What force do photons control?
What force do gluons control?
What force do W and Z particles control?
What are matter particles called?
What are the two types of particles?
Bosons and fermions
What are the three types of fermions
What are the three types of lepton
What are the two types of hadrions?
Baryons and mesons
What are the differences between baryons and mesons?
Baryons are made of three quarks and are strong, stable and long lived.
Mesons are made of two quarks and are unstable and short lived.
What are the six types of quark?
What is antimatter?
Particles which are identical in every way to their antiparticle apart from charge
What are antiparticles of electrons called?
What happens when a particle and its antiparticle meet?
They annihilate each other
How do particle accelerators work?
Strong magnetic fields deflect particles in a circular motion
Rapidly changing electric fields allow particles to accelerate
Explain the evidence for antimatter?
When a particle hits a target it splits into two particles which are identical in every way except charge
Which particles have neutrinos?
Explain the evidence for neutrinos?
During beta decay momentum appeared not to be conserved. Therefore it was concluded that a small particle moving at very high speeds must be produced to allow momentum to be conserved
What is a field?
A region of space where a force is felt without being touched
What were the results of Rutherford’s scattering experiment and what did this prove about particles?
1. Most of the alpha particles went straight through the gold foil - most of the atom is empty space.
2. Some were deflected by a small amount - the nucleus of the atom has a positive charge (like charges repel)
3. A small portion was deflected be a large amount - most of the atom’s mass is in the nucleus
What are the coolant and containment issues in nuclear fusion reactions?
Coolant materials form a blanket around the vessel absorbing the neutrons and the heat
Containment - the hot plasma is kept away from he vessel walls using very strong magnetic fields
What is photoelectric emission?
When electromagnetic radiation of a suitable frequency is incident on a clean metal surface causing electrons to be emitted from the surface
How does the photoelectric effect support light as a particle?
If light was a wave (constant stream of energy) then after enough time, enough energy would be supplied to cause an electron to be emitted. This doesn’t happen therefore light must be particles which either have enough energy or don’t
What is threshold frequency?
The minimum frequency of a photon required to cause photoemission
What is work function?
The minimum energy required to cause photoemission
What is irradiance?
A measure of the energy incident per unit surface area per second
What is the unit of irradiance?
What are coherent waves?
Ones that have a constant phase relationship and have the same frequency, wavelength and velocity
What is constructive interference?
It occurs when two waves are in phase - the crests of two waves and the troughs of two waves meet
What is destructive interference?
Two waves are out of phase - the crests of one wave meets the troughs of another
What are the differences between white light through a diffraction grating and a prism?
- forms a spectrum by refraction
- single spectrum produced
- red light is least deviated
- forms a spectrum by the interference of light which has diffracted as it passes through the slits
- many spectra are produced
- red light is most deviated
What is refraction?
The change in speed of light as it travels from one transparent material to another
What does refractive index tell us?
How much light will change in speed and therefore change in direction.
The higher the refractive index the higher the change in speed
What is the definition of refractive index?
The ratio of the sin of the angle of incidence in a vacuum to the sin of the angle of refraction in the medium
How is a line emission spectrum produced?
When an electron changes energy levels energy is released. If it is a large transition lots of energy is released and the photon emitted will have a high frequency and a short wavelength therefore it will be in the violet end of the spectrum.
How is an emission spectrum produced?
An electron starts off in a lower energy level.
It will gain energy from an incident photon.
If the energy from the photon is enough to allow the electron to make an upwards transition the electron will absorb the energy and move up